drivers/net/xen-netback/netback.c

   1 /*
   2  * Back-end of the driver for virtual network devices. This portion of the
   3  * driver exports a 'unified' network-device interface that can be accessed
   4  * by any operating system that implements a compatible front end. A
   5  * reference front-end implementation can be found in:
   6  *  drivers/net/xen-netfront.c
   7  *
   8  * Copyright (c) 2002-2005, K A Fraser
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include "common.h"
  36
  37 #include <linux/kthread.h>
  38 #include <linux/if_vlan.h>
  39 #include <linux/udp.h>
  40
  41 #include <net/tcp.h>
  42
  43 #include <xen/xen.h>
  44 #include <xen/events.h>
  45 #include <xen/interface/memory.h>
  46
  47 #include <asm/xen/hypercall.h>
  48 #include <asm/xen/page.h>
  49
  50 /* Provide an option to disable split event channels at load time as
  51  * event channels are limited resource. Split event channels are
  52  * enabled by default.
  53  */
  54 bool separate_tx_rx_irq = 1;
  55 module_param(separate_tx_rx_irq, bool, 0644);
  56
  57 /*
  58  * This is the maximum slots a skb can have. If a guest sends a skb
  59  * which exceeds this limit it is considered malicious.
  60  */
  61 #define FATAL_SKB_SLOTS_DEFAULT 20
  62 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
  63 module_param(fatal_skb_slots, uint, 0444);
  64
  65 /*
  66  * To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
  67  * the maximum slots a valid packet can use. Now this value is defined
  68  * to be XEN_NETIF_NR_SLOTS_MIN, which is supposed to be supported by
  69  * all backend.
  70  */
  71 #define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
  72
  73 typedef unsigned int pending_ring_idx_t;
  74 #define INVALID_PENDING_RING_IDX (~0U)
  75
  76 struct pending_tx_info {
  77         struct xen_netif_tx_request req; /* coalesced tx request */
  78         struct xenvif *vif;
  79         pending_ring_idx_t head; /* head != INVALID_PENDING_RING_IDX
  80                                   * if it is head of one or more tx
  81                                   * reqs
  82                                   */
  83 };
  84
  85 struct netbk_rx_meta {
  86         int id;
  87         int size;
  88         int gso_size;
  89 };
  90
  91 #define MAX_PENDING_REQS 256
  92
  93 /* Discriminate from any valid pending_idx value. */
  94 #define INVALID_PENDING_IDX 0xFFFF
  95
  96 #define MAX_BUFFER_OFFSET PAGE_SIZE
  97
  98 /* extra field used in struct page */
  99 union page_ext {
 100         struct {
 101 #if BITS_PER_LONG < 64
 102 #define IDX_WIDTH   8
 103 #define GROUP_WIDTH (BITS_PER_LONG - IDX_WIDTH)
 104                 unsigned int group:GROUP_WIDTH;
 105                 unsigned int idx:IDX_WIDTH;
 106 #else
 107                 unsigned int group, idx;
 108 #endif
 109         } e;
 110         void *mapping;
 111 };
 112
 113 struct xen_netbk {
 114         wait_queue_head_t wq;
 115         struct task_struct *task;
 116
 117         struct sk_buff_head rx_queue;
 118         struct sk_buff_head tx_queue;
 119
 120         struct timer_list net_timer;
 121
 122         struct page *mmap_pages[MAX_PENDING_REQS];
 123
 124         pending_ring_idx_t pending_prod;
 125         pending_ring_idx_t pending_cons;
 126         struct list_head net_schedule_list;
 127
 128         /* Protect the net_schedule_list in netif. */
 129         spinlock_t net_schedule_list_lock;
 130
 131         atomic_t netfront_count;
 132
 133         struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
 134         /* Coalescing tx requests before copying makes number of grant
 135          * copy ops greater or equal to number of slots required. In
 136          * worst case a tx request consumes 2 gnttab_copy.
 137          */
 138         struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
 139
 140         u16 pending_ring[MAX_PENDING_REQS];
 141
 142         /*
 143          * Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
 144          * head/fragment page uses 2 copy operations because it
 145          * straddles two buffers in the frontend.
 146          */
 147         struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
 148         struct netbk_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
 149 };
 150
 151 static struct xen_netbk *xen_netbk;
 152 static int xen_netbk_group_nr;
 153
 154 /*
 155  * If head != INVALID_PENDING_RING_IDX, it means this tx request is head of
 156  * one or more merged tx requests, otherwise it is the continuation of
 157  * previous tx request.
 158  */
 159 static inline int pending_tx_is_head(struct xen_netbk *netbk, RING_IDX idx)
 160 {
 161         return netbk->pending_tx_info[idx].head != INVALID_PENDING_RING_IDX;
 162 }
 163
 164 void xen_netbk_add_xenvif(struct xenvif *vif)
 165 {
 166         int i;
 167         int min_netfront_count;
 168         int min_group = 0;
 169         struct xen_netbk *netbk;
 170
 171         min_netfront_count = atomic_read(&xen_netbk[0].netfront_count);
 172         for (i = 0; i < xen_netbk_group_nr; i++) {
 173                 int netfront_count = atomic_read(&xen_netbk[i].netfront_count);
 174                 if (netfront_count < min_netfront_count) {
 175                         min_group = i;
 176                         min_netfront_count = netfront_count;
 177                 }
 178         }
 179
 180         netbk = &xen_netbk[min_group];
 181
 182         vif->netbk = netbk;
 183         atomic_inc(&netbk->netfront_count);
 184 }
 185
 186 void xen_netbk_remove_xenvif(struct xenvif *vif)
 187 {
 188         struct xen_netbk *netbk = vif->netbk;
 189         vif->netbk = NULL;
 190         atomic_dec(&netbk->netfront_count);
 191 }
 192
 193 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
 194                                   u8 status);
 195 static void make_tx_response(struct xenvif *vif,
 196                              struct xen_netif_tx_request *txp,
 197                              s8       st);
 198 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
 199                                              u16      id,
 200                                              s8       st,
 201                                              u16      offset,
 202                                              u16      size,
 203                                              u16      flags);
 204
 205 static inline unsigned long idx_to_pfn(struct xen_netbk *netbk,
 206                                        u16 idx)
 207 {
 208         return page_to_pfn(netbk->mmap_pages[idx]);
 209 }
 210
 211 static inline unsigned long idx_to_kaddr(struct xen_netbk *netbk,
 212                                          u16 idx)
 213 {
 214         return (unsigned long)pfn_to_kaddr(idx_to_pfn(netbk, idx));
 215 }
 216
 217 /* extra field used in struct page */
 218 static inline void set_page_ext(struct page *pg, struct xen_netbk *netbk,
 219                                 unsigned int idx)
 220 {
 221         unsigned int group = netbk - xen_netbk;
 222         union page_ext ext = { .e = { .group = group + 1, .idx = idx } };
 223
 224         BUILD_BUG_ON(sizeof(ext) > sizeof(ext.mapping));
 225         pg->mapping = ext.mapping;
 226 }
 227
 228 static int get_page_ext(struct page *pg,
 229                         unsigned int *pgroup, unsigned int *pidx)
 230 {
 231         union page_ext ext = { .mapping = pg->mapping };
 232         struct xen_netbk *netbk;
 233         unsigned int group, idx;
 234
 235         group = ext.e.group - 1;
 236
 237         if (group < 0 || group >= xen_netbk_group_nr)
 238                 return 0;
 239
 240         netbk = &xen_netbk[group];
 241
 242         idx = ext.e.idx;
 243
 244         if ((idx < 0) || (idx >= MAX_PENDING_REQS))
 245                 return 0;
 246
 247         if (netbk->mmap_pages[idx] != pg)
 248                 return 0;
 249
 250         *pgroup = group;
 251         *pidx = idx;
 252
 253         return 1;
 254 }
 255
 256 /*
 257  * This is the amount of packet we copy rather than map, so that the
 258  * guest can't fiddle with the contents of the headers while we do
 259  * packet processing on them (netfilter, routing, etc).
 260  */
 261 #define PKT_PROT_LEN    (ETH_HLEN + \
 262                          VLAN_HLEN + \
 263                          sizeof(struct iphdr) + MAX_IPOPTLEN + \
 264                          sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
 265
 266 static u16 frag_get_pending_idx(skb_frag_t *frag)
 267 {
 268         return (u16)frag->page_offset;
 269 }
 270
 271 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 272 {
 273         frag->page_offset = pending_idx;
 274 }
 275
 276 static inline pending_ring_idx_t pending_index(unsigned i)
 277 {
 278         return i & (MAX_PENDING_REQS-1);
 279 }
 280
 281 static inline pending_ring_idx_t nr_pending_reqs(struct xen_netbk *netbk)
 282 {
 283         return MAX_PENDING_REQS -
 284                 netbk->pending_prod + netbk->pending_cons;
 285 }
 286
 287 static void xen_netbk_kick_thread(struct xen_netbk *netbk)
 288 {
 289         wake_up(&netbk->wq);
 290 }
 291
 292 static int max_required_rx_slots(struct xenvif *vif)
 293 {
 294         int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
 295
 296         /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 297         if (vif->can_sg || vif->gso || vif->gso_prefix)
 298                 max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
 299
 300         return max;
 301 }
 302
 303 int xen_netbk_rx_ring_full(struct xenvif *vif)
 304 {
 305         RING_IDX peek   = vif->rx_req_cons_peek;
 306         RING_IDX needed = max_required_rx_slots(vif);
 307
 308         return ((vif->rx.sring->req_prod - peek) < needed) ||
 309                ((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
 310 }
 311
 312 int xen_netbk_must_stop_queue(struct xenvif *vif)
 313 {
 314         if (!xen_netbk_rx_ring_full(vif))
 315                 return 0;
 316
 317         vif->rx.sring->req_event = vif->rx_req_cons_peek +
 318                 max_required_rx_slots(vif);
 319         mb(); /* request notification /then/ check the queue */
 320
 321         return xen_netbk_rx_ring_full(vif);
 322 }
 323
 324 /*
 325  * Returns true if we should start a new receive buffer instead of
 326  * adding 'size' bytes to a buffer which currently contains 'offset'
 327  * bytes.
 328  */
 329 static bool start_new_rx_buffer(int offset, unsigned long size, int head)
 330 {
 331         /* simple case: we have completely filled the current buffer. */
 332         if (offset == MAX_BUFFER_OFFSET)
 333                 return true;
 334
 335         /*
 336          * complex case: start a fresh buffer if the current frag
 337          * would overflow the current buffer but only if:
 338          *     (i)   this frag would fit completely in the next buffer
 339          * and (ii)  there is already some data in the current buffer
 340          * and (iii) this is not the head buffer.
 341          *
 342          * Where:
 343          * - (i) stops us splitting a frag into two copies
 344          *   unless the frag is too large for a single buffer.
 345          * - (ii) stops us from leaving a buffer pointlessly empty.
 346          * - (iii) stops us leaving the first buffer
 347          *   empty. Strictly speaking this is already covered
 348          *   by (ii) but is explicitly checked because
 349          *   netfront relies on the first buffer being
 350          *   non-empty and can crash otherwise.
 351          *
 352          * This means we will effectively linearise small
 353          * frags but do not needlessly split large buffers
 354          * into multiple copies tend to give large frags their
 355          * own buffers as before.
 356          */
 357         if ((offset + size > MAX_BUFFER_OFFSET) &&
 358             (size <= MAX_BUFFER_OFFSET) && offset && !head)
 359                 return true;
 360
 361         return false;
 362 }
 363
 364 /*
 365  * Figure out how many ring slots we're going to need to send @skb to
 366  * the guest. This function is essentially a dry run of
 367  * netbk_gop_frag_copy.
 368  */
 369 unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
 370 {
 371         unsigned int count;
 372         int i, copy_off;
 373
 374         count = DIV_ROUND_UP(skb_headlen(skb), PAGE_SIZE);
 375
 376         copy_off = skb_headlen(skb) % PAGE_SIZE;
 377
 378         if (skb_shinfo(skb)->gso_size)
 379                 count++;
 380
 381         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 382                 unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
 383                 unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
 384                 unsigned long bytes;
 385
 386                 offset &= ~PAGE_MASK;
 387
 388                 while (size > 0) {
 389                         BUG_ON(offset >= PAGE_SIZE);
 390                         BUG_ON(copy_off > MAX_BUFFER_OFFSET);
 391
 392                         bytes = PAGE_SIZE - offset;
 393
 394                         if (bytes > size)
 395                                 bytes = size;
 396
 397                         if (start_new_rx_buffer(copy_off, bytes, 0)) {
 398                                 count++;
 399                                 copy_off = 0;
 400                         }
 401
 402                         if (copy_off + bytes > MAX_BUFFER_OFFSET)
 403                                 bytes = MAX_BUFFER_OFFSET - copy_off;
 404
 405                         copy_off += bytes;
 406
 407                         offset += bytes;
 408                         size -= bytes;
 409
 410                         if (offset == PAGE_SIZE)
 411                                 offset = 0;
 412                 }
 413         }
 414         return count;
 415 }
 416
 417 struct netrx_pending_operations {
 418         unsigned copy_prod, copy_cons;
 419         unsigned meta_prod, meta_cons;
 420         struct gnttab_copy *copy;
 421         struct netbk_rx_meta *meta;
 422         int copy_off;
 423         grant_ref_t copy_gref;
 424 };
 425
 426 static struct netbk_rx_meta *get_next_rx_buffer(struct xenvif *vif,
 427                                                 struct netrx_pending_operations *npo)
 428 {
 429         struct netbk_rx_meta *meta;
 430         struct xen_netif_rx_request *req;
 431
 432         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 433
 434         meta = npo->meta + npo->meta_prod++;
 435         meta->gso_size = 0;
 436         meta->size = 0;
 437         meta->id = req->id;
 438
 439         npo->copy_off = 0;
 440         npo->copy_gref = req->gref;
 441
 442         return meta;
 443 }
 444
 445 /*
 446  * Set up the grant operations for this fragment. If it's a flipping
 447  * interface, we also set up the unmap request from here.
 448  */
 449 static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 450                                 struct netrx_pending_operations *npo,
 451                                 struct page *page, unsigned long size,
 452                                 unsigned long offset, int *head)
 453 {
 454         struct gnttab_copy *copy_gop;
 455         struct netbk_rx_meta *meta;
 456         /*
 457          * These variables are used iff get_page_ext returns true,
 458          * in which case they are guaranteed to be initialized.
 459          */
 460         unsigned int uninitialized_var(group), uninitialized_var(idx);
 461         int foreign = get_page_ext(page, &group, &idx);
 462         unsigned long bytes;
 463
 464         /* Data must not cross a page boundary. */
 465         BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 466
 467         meta = npo->meta + npo->meta_prod - 1;
 468
 469         /* Skip unused frames from start of page */
 470         page += offset >> PAGE_SHIFT;
 471         offset &= ~PAGE_MASK;
 472
 473         while (size > 0) {
 474                 BUG_ON(offset >= PAGE_SIZE);
 475                 BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 476
 477                 bytes = PAGE_SIZE - offset;
 478
 479                 if (bytes > size)
 480                         bytes = size;
 481
 482                 if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
 483                         /*
 484                          * Netfront requires there to be some data in the head
 485                          * buffer.
 486                          */
 487                         BUG_ON(*head);
 488
 489                         meta = get_next_rx_buffer(vif, npo);
 490                 }
 491
 492                 if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 493                         bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 494
 495                 copy_gop = npo->copy + npo->copy_prod++;
 496                 copy_gop->flags = GNTCOPY_dest_gref;
 497                 if (foreign) {
 498                         struct xen_netbk *netbk = &xen_netbk[group];
 499                         struct pending_tx_info *src_pend;
 500
 501                         src_pend = &netbk->pending_tx_info[idx];
 502
 503                         copy_gop->source.domid = src_pend->vif->domid;
 504                         copy_gop->source.u.ref = src_pend->req.gref;
 505                         copy_gop->flags |= GNTCOPY_source_gref;
 506                 } else {
 507                         void *vaddr = page_address(page);
 508                         copy_gop->source.domid = DOMID_SELF;
 509                         copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
 510                 }
 511                 copy_gop->source.offset = offset;
 512                 copy_gop->dest.domid = vif->domid;
 513
 514                 copy_gop->dest.offset = npo->copy_off;
 515                 copy_gop->dest.u.ref = npo->copy_gref;
 516                 copy_gop->len = bytes;
 517
 518                 npo->copy_off += bytes;
 519                 meta->size += bytes;
 520
 521                 offset += bytes;
 522                 size -= bytes;
 523
 524                 /* Next frame */
 525                 if (offset == PAGE_SIZE && size) {
 526                         BUG_ON(!PageCompound(page));
 527                         page++;
 528                         offset = 0;
 529                 }
 530
 531                 /* Leave a gap for the GSO descriptor. */
 532                 if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
 533                         vif->rx.req_cons++;
 534
 535                 *head = 0; /* There must be something in this buffer now. */
 536
 537         }
 538 }
 539
 540 /*
 541  * Prepare an SKB to be transmitted to the frontend.
 542  *
 543  * This function is responsible for allocating grant operations, meta
 544  * structures, etc.
 545  *
 546  * It returns the number of meta structures consumed. The number of
 547  * ring slots used is always equal to the number of meta slots used
 548  * plus the number of GSO descriptors used. Currently, we use either
 549  * zero GSO descriptors (for non-GSO packets) or one descriptor (for
 550  * frontend-side LRO).
 551  */
 552 static int netbk_gop_skb(struct sk_buff *skb,
 553                          struct netrx_pending_operations *npo)
 554 {
 555         struct xenvif *vif = netdev_priv(skb->dev);
 556         int nr_frags = skb_shinfo(skb)->nr_frags;
 557         int i;
 558         struct xen_netif_rx_request *req;
 559         struct netbk_rx_meta *meta;
 560         unsigned char *data;
 561         int head = 1;
 562         int old_meta_prod;
 563
 564         old_meta_prod = npo->meta_prod;
 565
 566         /* Set up a GSO prefix descriptor, if necessary */
 567         if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
 568                 req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 569                 meta = npo->meta + npo->meta_prod++;
 570                 meta->gso_size = skb_shinfo(skb)->gso_size;
 571                 meta->size = 0;
 572                 meta->id = req->id;
 573         }
 574
 575         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 576         meta = npo->meta + npo->meta_prod++;
 577
 578         if (!vif->gso_prefix)
 579                 meta->gso_size = skb_shinfo(skb)->gso_size;
 580         else
 581                 meta->gso_size = 0;
 582
 583         meta->size = 0;
 584         meta->id = req->id;
 585         npo->copy_off = 0;
 586         npo->copy_gref = req->gref;
 587
 588         data = skb->data;
 589         while (data < skb_tail_pointer(skb)) {
 590                 unsigned int offset = offset_in_page(data);
 591                 unsigned int len = PAGE_SIZE - offset;
 592
 593                 if (data + len > skb_tail_pointer(skb))
 594                         len = skb_tail_pointer(skb) - data;
 595
 596                 netbk_gop_frag_copy(vif, skb, npo,
 597                                     virt_to_page(data), len, offset, &head);
 598                 data += len;
 599         }
 600
 601         for (i = 0; i < nr_frags; i++) {
 602                 netbk_gop_frag_copy(vif, skb, npo,
 603                                     skb_frag_page(&skb_shinfo(skb)->frags[i]),
 604                                     skb_frag_size(&skb_shinfo(skb)->frags[i]),
 605                                     skb_shinfo(skb)->frags[i].page_offset,
 606                                     &head);
 607         }
 608
 609         return npo->meta_prod - old_meta_prod;
 610 }
 611
 612 /*
 613  * This is a twin to netbk_gop_skb.  Assume that netbk_gop_skb was
 614  * used to set up the operations on the top of
 615  * netrx_pending_operations, which have since been done.  Check that
 616  * they didn't give any errors and advance over them.
 617  */
 618 static int netbk_check_gop(struct xenvif *vif, int nr_meta_slots,
 619                            struct netrx_pending_operations *npo)
 620 {
 621         struct gnttab_copy     *copy_op;
 622         int status = XEN_NETIF_RSP_OKAY;
 623         int i;
 624
 625         for (i = 0; i < nr_meta_slots; i++) {
 626                 copy_op = npo->copy + npo->copy_cons++;
 627                 if (copy_op->status != GNTST_okay) {
 628                         netdev_dbg(vif->dev,
 629                                    "Bad status %d from copy to DOM%d.\n",
 630                                    copy_op->status, vif->domid);
 631                         status = XEN_NETIF_RSP_ERROR;
 632                 }
 633         }
 634
 635         return status;
 636 }
 637
 638 static void netbk_add_frag_responses(struct xenvif *vif, int status,
 639                                      struct netbk_rx_meta *meta,
 640                                      int nr_meta_slots)
 641 {
 642         int i;
 643         unsigned long offset;
 644
 645         /* No fragments used */
 646         if (nr_meta_slots <= 1)
 647                 return;
 648
 649         nr_meta_slots--;
 650
 651         for (i = 0; i < nr_meta_slots; i++) {
 652                 int flags;
 653                 if (i == nr_meta_slots - 1)
 654                         flags = 0;
 655                 else
 656                         flags = XEN_NETRXF_more_data;
 657
 658                 offset = 0;
 659                 make_rx_response(vif, meta[i].id, status, offset,
 660                                  meta[i].size, flags);
 661         }
 662 }
 663
 664 struct skb_cb_overlay {
 665         int meta_slots_used;
 666 };
 667
 668 static void xen_netbk_rx_action(struct xen_netbk *netbk)
 669 {
 670         struct xenvif *vif = NULL, *tmp;
 671         s8 status;
 672         u16 flags;
 673         struct xen_netif_rx_response *resp;
 674         struct sk_buff_head rxq;
 675         struct sk_buff *skb;
 676         LIST_HEAD(notify);
 677         int ret;
 678         int nr_frags;
 679         int count;
 680         unsigned long offset;
 681         struct skb_cb_overlay *sco;
 682
 683         struct netrx_pending_operations npo = {
 684                 .copy  = netbk->grant_copy_op,
 685                 .meta  = netbk->meta,
 686         };
 687
 688         skb_queue_head_init(&rxq);
 689
 690         count = 0;
 691
 692         while ((skb = skb_dequeue(&netbk->rx_queue)) != NULL) {
 693                 vif = netdev_priv(skb->dev);
 694                 nr_frags = skb_shinfo(skb)->nr_frags;
 695
 696                 sco = (struct skb_cb_overlay *)skb->cb;
 697                 sco->meta_slots_used = netbk_gop_skb(skb, &npo);
 698
 699                 count += nr_frags + 1;
 700
 701                 __skb_queue_tail(&rxq, skb);
 702
 703                 /* Filled the batch queue? */
 704                 /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 705                 if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
 706                         break;
 707         }
 708
 709         BUG_ON(npo.meta_prod > ARRAY_SIZE(netbk->meta));
 710
 711         if (!npo.copy_prod)
 712                 return;
 713
 714         BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
 715         gnttab_batch_copy(netbk->grant_copy_op, npo.copy_prod);
 716
 717         while ((skb = __skb_dequeue(&rxq)) != NULL) {
 718                 sco = (struct skb_cb_overlay *)skb->cb;
 719
 720                 vif = netdev_priv(skb->dev);
 721
 722                 if (netbk->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
 723                         resp = RING_GET_RESPONSE(&vif->rx,
 724                                                 vif->rx.rsp_prod_pvt++);
 725
 726                         resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
 727
 728                         resp->offset = netbk->meta[npo.meta_cons].gso_size;
 729                         resp->id = netbk->meta[npo.meta_cons].id;
 730                         resp->status = sco->meta_slots_used;
 731
 732                         npo.meta_cons++;
 733                         sco->meta_slots_used--;
 734                 }
 735
 736
 737                 vif->dev->stats.tx_bytes += skb->len;
 738                 vif->dev->stats.tx_packets++;
 739
 740                 status = netbk_check_gop(vif, sco->meta_slots_used, &npo);
 741
 742                 if (sco->meta_slots_used == 1)
 743                         flags = 0;
 744                 else
 745                         flags = XEN_NETRXF_more_data;
 746
 747                 if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
 748                         flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
 749                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 750                         /* remote but checksummed. */
 751                         flags |= XEN_NETRXF_data_validated;
 752
 753                 offset = 0;
 754                 resp = make_rx_response(vif, netbk->meta[npo.meta_cons].id,
 755                                         status, offset,
 756                                         netbk->meta[npo.meta_cons].size,
 757                                         flags);
 758
 759                 if (netbk->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
 760                         struct xen_netif_extra_info *gso =
 761                                 (struct xen_netif_extra_info *)
 762                                 RING_GET_RESPONSE(&vif->rx,
 763                                                   vif->rx.rsp_prod_pvt++);
 764
 765                         resp->flags |= XEN_NETRXF_extra_info;
 766
 767                         gso->u.gso.size = netbk->meta[npo.meta_cons].gso_size;
 768                         gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
 769                         gso->u.gso.pad = 0;
 770                         gso->u.gso.features = 0;
 771
 772                         gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
 773                         gso->flags = 0;
 774                 }
 775
 776                 netbk_add_frag_responses(vif, status,
 777                                          netbk->meta + npo.meta_cons + 1,
 778                                          sco->meta_slots_used);
 779
 780                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
 781
 782                 xenvif_notify_tx_completion(vif);
 783
 784                 if (ret && list_empty(&vif->notify_list))
 785                         list_add_tail(&vif->notify_list, &notify);
 786                 else
 787                         xenvif_put(vif);
 788                 npo.meta_cons += sco->meta_slots_used;
 789                 dev_kfree_skb(skb);
 790         }
 791
 792         list_for_each_entry_safe(vif, tmp, &notify, notify_list) {
 793                 notify_remote_via_irq(vif->rx_irq);
 794                 list_del_init(&vif->notify_list);
 795                 xenvif_put(vif);
 796         }
 797
 798         /* More work to do? */
 799         if (!skb_queue_empty(&netbk->rx_queue) &&
 800                         !timer_pending(&netbk->net_timer))
 801                 xen_netbk_kick_thread(netbk);
 802 }
 803
 804 void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
 805 {
 806         struct xen_netbk *netbk = vif->netbk;
 807
 808         skb_queue_tail(&netbk->rx_queue, skb);
 809
 810         xen_netbk_kick_thread(netbk);
 811 }
 812
 813 static void xen_netbk_alarm(unsigned long data)
 814 {
 815         struct xen_netbk *netbk = (struct xen_netbk *)data;
 816         xen_netbk_kick_thread(netbk);
 817 }
 818
 819 static int __on_net_schedule_list(struct xenvif *vif)
 820 {
 821         return !list_empty(&vif->schedule_list);
 822 }
 823
 824 /* Must be called with net_schedule_list_lock held */
 825 static void remove_from_net_schedule_list(struct xenvif *vif)
 826 {
 827         if (likely(__on_net_schedule_list(vif))) {
 828                 list_del_init(&vif->schedule_list);
 829                 xenvif_put(vif);
 830         }
 831 }
 832
 833 static struct xenvif *poll_net_schedule_list(struct xen_netbk *netbk)
 834 {
 835         struct xenvif *vif = NULL;
 836
 837         spin_lock_irq(&netbk->net_schedule_list_lock);
 838         if (list_empty(&netbk->net_schedule_list))
 839                 goto out;
 840
 841         vif = list_first_entry(&netbk->net_schedule_list,
 842                                struct xenvif, schedule_list);
 843         if (!vif)
 844                 goto out;
 845
 846         xenvif_get(vif);
 847
 848         remove_from_net_schedule_list(vif);
 849 out:
 850         spin_unlock_irq(&netbk->net_schedule_list_lock);
 851         return vif;
 852 }
 853
 854 void xen_netbk_schedule_xenvif(struct xenvif *vif)
 855 {
 856         unsigned long flags;
 857         struct xen_netbk *netbk = vif->netbk;
 858
 859         if (__on_net_schedule_list(vif))
 860                 goto kick;
 861
 862         spin_lock_irqsave(&netbk->net_schedule_list_lock, flags);
 863         if (!__on_net_schedule_list(vif) &&
 864             likely(xenvif_schedulable(vif))) {
 865                 list_add_tail(&vif->schedule_list, &netbk->net_schedule_list);
 866                 xenvif_get(vif);
 867         }
 868         spin_unlock_irqrestore(&netbk->net_schedule_list_lock, flags);
 869
 870 kick:
 871         smp_mb();
 872         if ((nr_pending_reqs(netbk) < (MAX_PENDING_REQS/2)) &&
 873             !list_empty(&netbk->net_schedule_list))
 874                 xen_netbk_kick_thread(netbk);
 875 }
 876
 877 void xen_netbk_deschedule_xenvif(struct xenvif *vif)
 878 {
 879         struct xen_netbk *netbk = vif->netbk;
 880         spin_lock_irq(&netbk->net_schedule_list_lock);
 881         remove_from_net_schedule_list(vif);
 882         spin_unlock_irq(&netbk->net_schedule_list_lock);
 883 }
 884
 885 void xen_netbk_check_rx_xenvif(struct xenvif *vif)
 886 {
 887         int more_to_do;
 888
 889         RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
 890
 891         if (more_to_do)
 892                 xen_netbk_schedule_xenvif(vif);
 893 }
 894
 895 static void tx_add_credit(struct xenvif *vif)
 896 {
 897         unsigned long max_burst, max_credit;
 898
 899         /*
 900          * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 901          * Otherwise the interface can seize up due to insufficient credit.
 902          */
 903         max_burst = RING_GET_REQUEST(&vif->tx, vif->tx.req_cons)->size;
 904         max_burst = min(max_burst, 131072UL);
 905         max_burst = max(max_burst, vif->credit_bytes);
 906
 907         /* Take care that adding a new chunk of credit doesn't wrap to zero. */
 908         max_credit = vif->remaining_credit + vif->credit_bytes;
 909         if (max_credit < vif->remaining_credit)
 910                 max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
 911
 912         vif->remaining_credit = min(max_credit, max_burst);
 913 }
 914
 915 static void tx_credit_callback(unsigned long data)
 916 {
 917         struct xenvif *vif = (struct xenvif *)data;
 918         tx_add_credit(vif);
 919         xen_netbk_check_rx_xenvif(vif);
 920 }
 921
 922 static void netbk_tx_err(struct xenvif *vif,
 923                          struct xen_netif_tx_request *txp, RING_IDX end)
 924 {
 925         RING_IDX cons = vif->tx.req_cons;
 926
 927         do {
 928                 make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
 929                 if (cons == end)
 930                         break;
 931                 txp = RING_GET_REQUEST(&vif->tx, cons++);
 932         } while (1);
 933         vif->tx.req_cons = cons;
 934         xen_netbk_check_rx_xenvif(vif);
 935         xenvif_put(vif);
 936 }
 937
 938 static void netbk_fatal_tx_err(struct xenvif *vif)
 939 {
 940         netdev_err(vif->dev, "fatal error; disabling device\n");
 941         xenvif_carrier_off(vif);
 942         xenvif_put(vif);
 943 }
 944
 945 static int netbk_count_requests(struct xenvif *vif,
 946                                 struct xen_netif_tx_request *first,
 947                                 struct xen_netif_tx_request *txp,
 948                                 int work_to_do)
 949 {
 950         RING_IDX cons = vif->tx.req_cons;
 951         int slots = 0;
 952         int drop_err = 0;
 953         int more_data;
 954
 955         if (!(first->flags & XEN_NETTXF_more_data))
 956                 return 0;
 957
 958         do {
 959                 struct xen_netif_tx_request dropped_tx = { 0 };
 960
 961                 if (slots >= work_to_do) {
 962                         netdev_err(vif->dev,
 963                                    "Asked for %d slots but exceeds this limit\n",
 964                                    work_to_do);
 965                         netbk_fatal_tx_err(vif);
 966                         return -ENODATA;
 967                 }
 968
 969                 /* This guest is really using too many slots and
 970                  * considered malicious.
 971                  */
 972                 if (unlikely(slots >= fatal_skb_slots)) {
 973                         netdev_err(vif->dev,
 974                                    "Malicious frontend using %d slots, threshold %u\n",
 975                                    slots, fatal_skb_slots);
 976                         netbk_fatal_tx_err(vif);
 977                         return -E2BIG;
 978                 }
 979
 980                 /* Xen network protocol had implicit dependency on
 981                  * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
 982                  * the historical MAX_SKB_FRAGS value 18 to honor the
 983                  * same behavior as before. Any packet using more than
 984                  * 18 slots but less than fatal_skb_slots slots is
 985                  * dropped
 986                  */
 987                 if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
 988                         if (net_ratelimit())
 989                                 netdev_dbg(vif->dev,
 990                                            "Too many slots (%d) exceeding limit (%d), dropping packet\n",
 991                                            slots, XEN_NETBK_LEGACY_SLOTS_MAX);
 992                         drop_err = -E2BIG;
 993                 }
 994
 995                 if (drop_err)
 996                         txp = &dropped_tx;
 997
 998                 memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
 999                        sizeof(*txp));
1000
1001                 /* If the guest submitted a frame >= 64 KiB then
1002                  * first->size overflowed and following slots will
1003                  * appear to be larger than the frame.
1004                  *
1005                  * This cannot be fatal error as there are buggy
1006                  * frontends that do this.
1007                  *
1008                  * Consume all slots and drop the packet.
1009                  */
1010                 if (!drop_err && txp->size > first->size) {
1011                         if (net_ratelimit())
1012                                 netdev_dbg(vif->dev,
1013                                            "Invalid tx request, slot size %u > remaining size %u\n",
1014                                            txp->size, first->size);
1015                         drop_err = -EIO;
1016                 }
1017
1018                 first->size -= txp->size;
1019                 slots++;
1020
1021                 if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
1022                         netdev_err(vif->dev, "Cross page boundary, txp->offset: %x, size: %u\n",
1023                                  txp->offset, txp->size);
1024                         netbk_fatal_tx_err(vif);
1025                         return -EINVAL;
1026                 }
1027
1028                 more_data = txp->flags & XEN_NETTXF_more_data;
1029
1030                 if (!drop_err)
1031                         txp++;
1032
1033         } while (more_data);
1034
1035         if (drop_err) {
1036                 netbk_tx_err(vif, first, cons + slots);
1037                 return drop_err;
1038         }
1039
1040         return slots;
1041 }
1042
1043 static struct page *xen_netbk_alloc_page(struct xen_netbk *netbk,
1044                                          u16 pending_idx)
1045 {
1046         struct page *page;
1047         page = alloc_page(GFP_KERNEL|__GFP_COLD);
1048         if (!page)
1049                 return NULL;
1050         set_page_ext(page, netbk, pending_idx);
1051         netbk->mmap_pages[pending_idx] = page;
1052         return page;
1053 }
1054
1055 static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
1056                                                   struct xenvif *vif,
1057                                                   struct sk_buff *skb,
1058                                                   struct xen_netif_tx_request *txp,
1059                                                   struct gnttab_copy *gop)
1060 {
1061         struct skb_shared_info *shinfo = skb_shinfo(skb);
1062         skb_frag_t *frags = shinfo->frags;
1063         u16 pending_idx = *((u16 *)skb->data);
1064         u16 head_idx = 0;
1065         int slot, start;
1066         struct page *page;
1067         pending_ring_idx_t index, start_idx = 0;
1068         uint16_t dst_offset;
1069         unsigned int nr_slots;
1070         struct pending_tx_info *first = NULL;
1071
1072         /* At this point shinfo->nr_frags is in fact the number of
1073          * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
1074          */
1075         nr_slots = shinfo->nr_frags;
1076
1077         /* Skip first skb fragment if it is on same page as header fragment. */
1078         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1079
1080         /* Coalesce tx requests, at this point the packet passed in
1081          * should be <= 64K. Any packets larger than 64K have been
1082          * handled in netbk_count_requests().
1083          */
1084         for (shinfo->nr_frags = slot = start; slot < nr_slots;
1085              shinfo->nr_frags++) {
1086                 struct pending_tx_info *pending_tx_info =
1087                         netbk->pending_tx_info;
1088
1089                 page = alloc_page(GFP_KERNEL|__GFP_COLD);
1090                 if (!page)
1091                         goto err;
1092
1093                 dst_offset = 0;
1094                 first = NULL;
1095                 while (dst_offset < PAGE_SIZE && slot < nr_slots) {
1096                         gop->flags = GNTCOPY_source_gref;
1097
1098                         gop->source.u.ref = txp->gref;
1099                         gop->source.domid = vif->domid;
1100                         gop->source.offset = txp->offset;
1101
1102                         gop->dest.domid = DOMID_SELF;
1103
1104                         gop->dest.offset = dst_offset;
1105                         gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1106
1107                         if (dst_offset + txp->size > PAGE_SIZE) {
1108                                 /* This page can only merge a portion
1109                                  * of tx request. Do not increment any
1110                                  * pointer / counter here. The txp
1111                                  * will be dealt with in future
1112                                  * rounds, eventually hitting the
1113                                  * `else` branch.
1114                                  */
1115                                 gop->len = PAGE_SIZE - dst_offset;
1116                                 txp->offset += gop->len;
1117                                 txp->size -= gop->len;
1118                                 dst_offset += gop->len; /* quit loop */
1119                         } else {
1120                                 /* This tx request can be merged in the page */
1121                                 gop->len = txp->size;
1122                                 dst_offset += gop->len;
1123
1124                                 index = pending_index(netbk->pending_cons++);
1125
1126                                 pending_idx = netbk->pending_ring[index];
1127
1128                                 memcpy(&pending_tx_info[pending_idx].req, txp,
1129                                        sizeof(*txp));
1130                                 xenvif_get(vif);
1131
1132                                 pending_tx_info[pending_idx].vif = vif;
1133
1134                                 /* Poison these fields, corresponding
1135                                  * fields for head tx req will be set
1136                                  * to correct values after the loop.
1137                                  */
1138                                 netbk->mmap_pages[pending_idx] = (void *)(~0UL);
1139                                 pending_tx_info[pending_idx].head =
1140                                         INVALID_PENDING_RING_IDX;
1141
1142                                 if (!first) {
1143                                         first = &pending_tx_info[pending_idx];
1144                                         start_idx = index;
1145                                         head_idx = pending_idx;
1146                                 }
1147
1148                                 txp++;
1149                                 slot++;
1150                         }
1151
1152                         gop++;
1153                 }
1154
1155                 first->req.offset = 0;
1156                 first->req.size = dst_offset;
1157                 first->head = start_idx;
1158                 set_page_ext(page, netbk, head_idx);
1159                 netbk->mmap_pages[head_idx] = page;
1160                 frag_set_pending_idx(&frags[shinfo->nr_frags], head_idx);
1161         }
1162
1163         BUG_ON(shinfo->nr_frags > MAX_SKB_FRAGS);
1164
1165         return gop;
1166 err:
1167         /* Unwind, freeing all pages and sending error responses. */
1168         while (shinfo->nr_frags-- > start) {
1169                 xen_netbk_idx_release(netbk,
1170                                 frag_get_pending_idx(&frags[shinfo->nr_frags]),
1171                                 XEN_NETIF_RSP_ERROR);
1172         }
1173         /* The head too, if necessary. */
1174         if (start)
1175                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1176
1177         return NULL;
1178 }
1179
1180 static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,
1181                                   struct sk_buff *skb,
1182                                   struct gnttab_copy **gopp)
1183 {
1184         struct gnttab_copy *gop = *gopp;
1185         u16 pending_idx = *((u16 *)skb->data);
1186         struct skb_shared_info *shinfo = skb_shinfo(skb);
1187         struct pending_tx_info *tx_info;
1188         int nr_frags = shinfo->nr_frags;
1189         int i, err, start;
1190         u16 peek; /* peek into next tx request */
1191
1192         /* Check status of header. */
1193         err = gop->status;
1194         if (unlikely(err))
1195                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1196
1197         /* Skip first skb fragment if it is on same page as header fragment. */
1198         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1199
1200         for (i = start; i < nr_frags; i++) {
1201                 int j, newerr;
1202                 pending_ring_idx_t head;
1203
1204                 pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
1205                 tx_info = &netbk->pending_tx_info[pending_idx];
1206                 head = tx_info->head;
1207
1208                 /* Check error status: if okay then remember grant handle. */
1209                 do {
1210                         newerr = (++gop)->status;
1211                         if (newerr)
1212                                 break;
1213                         peek = netbk->pending_ring[pending_index(++head)];
1214                 } while (!pending_tx_is_head(netbk, peek));
1215
1216                 if (likely(!newerr)) {
1217                         /* Had a previous error? Invalidate this fragment. */
1218                         if (unlikely(err))
1219                                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1220                         continue;
1221                 }
1222
1223                 /* Error on this fragment: respond to client with an error. */
1224                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1225
1226                 /* Not the first error? Preceding frags already invalidated. */
1227                 if (err)
1228                         continue;
1229
1230                 /* First error: invalidate header and preceding fragments. */
1231                 pending_idx = *((u16 *)skb->data);
1232                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1233                 for (j = start; j < i; j++) {
1234                         pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
1235                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1236                 }
1237
1238                 /* Remember the error: invalidate all subsequent fragments. */
1239                 err = newerr;
1240         }
1241
1242         *gopp = gop + 1;
1243         return err;
1244 }
1245
1246 static void xen_netbk_fill_frags(struct xen_netbk *netbk, struct sk_buff *skb)
1247 {
1248         struct skb_shared_info *shinfo = skb_shinfo(skb);
1249         int nr_frags = shinfo->nr_frags;
1250         int i;
1251
1252         for (i = 0; i < nr_frags; i++) {
1253                 skb_frag_t *frag = shinfo->frags + i;
1254                 struct xen_netif_tx_request *txp;
1255                 struct page *page;
1256                 u16 pending_idx;
1257
1258                 pending_idx = frag_get_pending_idx(frag);
1259
1260                 txp = &netbk->pending_tx_info[pending_idx].req;
1261                 page = virt_to_page(idx_to_kaddr(netbk, pending_idx));
1262                 __skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
1263                 skb->len += txp->size;
1264                 skb->data_len += txp->size;
1265                 skb->truesize += txp->size;
1266
1267                 /* Take an extra reference to offset xen_netbk_idx_release */
1268                 get_page(netbk->mmap_pages[pending_idx]);
1269                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1270         }
1271 }
1272
1273 static int xen_netbk_get_extras(struct xenvif *vif,
1274                                 struct xen_netif_extra_info *extras,
1275                                 int work_to_do)
1276 {
1277         struct xen_netif_extra_info extra;
1278         RING_IDX cons = vif->tx.req_cons;
1279
1280         do {
1281                 if (unlikely(work_to_do-- <= 0)) {
1282                         netdev_err(vif->dev, "Missing extra info\n");
1283                         netbk_fatal_tx_err(vif);
1284                         return -EBADR;
1285                 }
1286
1287                 memcpy(&extra, RING_GET_REQUEST(&vif->tx, cons),
1288                        sizeof(extra));
1289                 if (unlikely(!extra.type ||
1290                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
1291                         vif->tx.req_cons = ++cons;
1292                         netdev_err(vif->dev,
1293                                    "Invalid extra type: %d\n", extra.type);
1294                         netbk_fatal_tx_err(vif);
1295                         return -EINVAL;
1296                 }
1297
1298                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
1299                 vif->tx.req_cons = ++cons;
1300         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
1301
1302         return work_to_do;
1303 }
1304
1305 static int netbk_set_skb_gso(struct xenvif *vif,
1306                              struct sk_buff *skb,
1307                              struct xen_netif_extra_info *gso)
1308 {
1309         if (!gso->u.gso.size) {
1310                 netdev_err(vif->dev, "GSO size must not be zero.\n");
1311                 netbk_fatal_tx_err(vif);
1312                 return -EINVAL;
1313         }
1314
1315         /* Currently only TCPv4 S.O. is supported. */
1316         if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
1317                 netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
1318                 netbk_fatal_tx_err(vif);
1319                 return -EINVAL;
1320         }
1321
1322         skb_shinfo(skb)->gso_size = gso->u.gso.size;
1323         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1324
1325         /* Header must be checked, and gso_segs computed. */
1326         skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1327         skb_shinfo(skb)->gso_segs = 0;
1328
1329         return 0;
1330 }
1331
1332 static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
1333 {
1334         struct iphdr *iph;
1335         int err = -EPROTO;
1336         int recalculate_partial_csum = 0;
1337
1338         /*
1339          * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
1340          * peers can fail to set NETRXF_csum_blank when sending a GSO
1341          * frame. In this case force the SKB to CHECKSUM_PARTIAL and
1342          * recalculate the partial checksum.
1343          */
1344         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
1345                 vif->rx_gso_checksum_fixup++;
1346                 skb->ip_summed = CHECKSUM_PARTIAL;
1347                 recalculate_partial_csum = 1;
1348         }
1349
1350         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
1351         if (skb->ip_summed != CHECKSUM_PARTIAL)
1352                 return 0;
1353
1354         if (skb->protocol != htons(ETH_P_IP))
1355                 goto out;
1356
1357         iph = (void *)skb->data;
1358         switch (iph->protocol) {
1359         case IPPROTO_TCP:
1360                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1361                                           offsetof(struct tcphdr, check)))
1362                         goto out;
1363
1364                 if (recalculate_partial_csum) {
1365                         struct tcphdr *tcph = tcp_hdr(skb);
1366                         tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1367                                                          skb->len - iph->ihl*4,
1368                                                          IPPROTO_TCP, 0);
1369                 }
1370                 break;
1371         case IPPROTO_UDP:
1372                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1373                                           offsetof(struct udphdr, check)))
1374                         goto out;
1375
1376                 if (recalculate_partial_csum) {
1377                         struct udphdr *udph = udp_hdr(skb);
1378                         udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1379                                                          skb->len - iph->ihl*4,
1380                                                          IPPROTO_UDP, 0);
1381                 }
1382                 break;
1383         default:
1384                 if (net_ratelimit())
1385                         netdev_err(vif->dev,
1386                                    "Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
1387                                    iph->protocol);
1388                 goto out;
1389         }
1390
1391         err = 0;
1392
1393 out:
1394         return err;
1395 }
1396
1397 static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
1398 {
1399         unsigned long now = jiffies;
1400         unsigned long next_credit =
1401                 vif->credit_timeout.expires +
1402                 msecs_to_jiffies(vif->credit_usec / 1000);
1403
1404         /* Timer could already be pending in rare cases. */
1405         if (timer_pending(&vif->credit_timeout))
1406                 return true;
1407
1408         /* Passed the point where we can replenish credit? */
1409         if (time_after_eq(now, next_credit)) {
1410                 vif->credit_timeout.expires = now;
1411                 tx_add_credit(vif);
1412         }
1413
1414         /* Still too big to send right now? Set a callback. */
1415         if (size > vif->remaining_credit) {
1416                 vif->credit_timeout.data     =
1417                         (unsigned long)vif;
1418                 vif->credit_timeout.function =
1419                         tx_credit_callback;
1420                 mod_timer(&vif->credit_timeout,
1421                           next_credit);
1422
1423                 return true;
1424         }
1425
1426         return false;
1427 }
1428
1429 static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
1430 {
1431         struct gnttab_copy *gop = netbk->tx_copy_ops, *request_gop;
1432         struct sk_buff *skb;
1433         int ret;
1434
1435         while ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
1436                 < MAX_PENDING_REQS) &&
1437                 !list_empty(&netbk->net_schedule_list)) {
1438                 struct xenvif *vif;
1439                 struct xen_netif_tx_request txreq;
1440                 struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
1441                 struct page *page;
1442                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
1443                 u16 pending_idx;
1444                 RING_IDX idx;
1445                 int work_to_do;
1446                 unsigned int data_len;
1447                 pending_ring_idx_t index;
1448
1449                 /* Get a netif from the list with work to do. */
1450                 vif = poll_net_schedule_list(netbk);
1451                 /* This can sometimes happen because the test of
1452                  * list_empty(net_schedule_list) at the top of the
1453                  * loop is unlocked.  Just go back and have another
1454                  * look.
1455                  */
1456                 if (!vif)
1457                         continue;
1458
1459                 if (vif->tx.sring->req_prod - vif->tx.req_cons >
1460                     XEN_NETIF_TX_RING_SIZE) {
1461                         netdev_err(vif->dev,
1462                                    "Impossible number of requests. "
1463                                    "req_prod %d, req_cons %d, size %ld\n",
1464                                    vif->tx.sring->req_prod, vif->tx.req_cons,
1465                                    XEN_NETIF_TX_RING_SIZE);
1466                         netbk_fatal_tx_err(vif);
1467                         continue;
1468                 }
1469
1470                 RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
1471                 if (!work_to_do) {
1472                         xenvif_put(vif);
1473                         continue;
1474                 }
1475
1476                 idx = vif->tx.req_cons;
1477                 rmb(); /* Ensure that we see the request before we copy it. */
1478                 memcpy(&txreq, RING_GET_REQUEST(&vif->tx, idx), sizeof(txreq));
1479
1480                 /* Credit-based scheduling. */
1481                 if (txreq.size > vif->remaining_credit &&
1482                     tx_credit_exceeded(vif, txreq.size)) {
1483                         xenvif_put(vif);
1484                         continue;
1485                 }
1486
1487                 vif->remaining_credit -= txreq.size;
1488
1489                 work_to_do--;
1490                 vif->tx.req_cons = ++idx;
1491
1492                 memset(extras, 0, sizeof(extras));
1493                 if (txreq.flags & XEN_NETTXF_extra_info) {
1494                         work_to_do = xen_netbk_get_extras(vif, extras,
1495                                                           work_to_do);
1496                         idx = vif->tx.req_cons;
1497                         if (unlikely(work_to_do < 0))
1498                                 continue;
1499                 }
1500
1501                 ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
1502                 if (unlikely(ret < 0))
1503                         continue;
1504
1505                 idx += ret;
1506
1507                 if (unlikely(txreq.size < ETH_HLEN)) {
1508                         netdev_dbg(vif->dev,
1509                                    "Bad packet size: %d\n", txreq.size);
1510                         netbk_tx_err(vif, &txreq, idx);
1511                         continue;
1512                 }
1513
1514                 /* No crossing a page as the payload mustn't fragment. */
1515                 if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
1516                         netdev_err(vif->dev,
1517                                    "txreq.offset: %x, size: %u, end: %lu\n",
1518                                    txreq.offset, txreq.size,
1519                                    (txreq.offset&~PAGE_MASK) + txreq.size);
1520                         netbk_fatal_tx_err(vif);
1521                         continue;
1522                 }
1523
1524                 index = pending_index(netbk->pending_cons);
1525                 pending_idx = netbk->pending_ring[index];
1526
1527                 data_len = (txreq.size > PKT_PROT_LEN &&
1528                             ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
1529                         PKT_PROT_LEN : txreq.size;
1530
1531                 skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
1532                                 GFP_ATOMIC | __GFP_NOWARN);
1533                 if (unlikely(skb == NULL)) {
1534                         netdev_dbg(vif->dev,
1535                                    "Can't allocate a skb in start_xmit.\n");
1536                         netbk_tx_err(vif, &txreq, idx);
1537                         break;
1538                 }
1539
1540                 /* Packets passed to netif_rx() must have some headroom. */
1541                 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
1542
1543                 if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
1544                         struct xen_netif_extra_info *gso;
1545                         gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
1546
1547                         if (netbk_set_skb_gso(vif, skb, gso)) {
1548                                 /* Failure in netbk_set_skb_gso is fatal. */
1549                                 kfree_skb(skb);
1550                                 continue;
1551                         }
1552                 }
1553
1554                 /* XXX could copy straight to head */
1555                 page = xen_netbk_alloc_page(netbk, pending_idx);
1556                 if (!page) {
1557                         kfree_skb(skb);
1558                         netbk_tx_err(vif, &txreq, idx);
1559                         continue;
1560                 }
1561
1562                 gop->source.u.ref = txreq.gref;
1563                 gop->source.domid = vif->domid;
1564                 gop->source.offset = txreq.offset;
1565
1566                 gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1567                 gop->dest.domid = DOMID_SELF;
1568                 gop->dest.offset = txreq.offset;
1569
1570                 gop->len = txreq.size;
1571                 gop->flags = GNTCOPY_source_gref;
1572
1573                 gop++;
1574
1575                 memcpy(&netbk->pending_tx_info[pending_idx].req,
1576                        &txreq, sizeof(txreq));
1577                 netbk->pending_tx_info[pending_idx].vif = vif;
1578                 netbk->pending_tx_info[pending_idx].head = index;
1579                 *((u16 *)skb->data) = pending_idx;
1580
1581                 __skb_put(skb, data_len);
1582
1583                 skb_shinfo(skb)->nr_frags = ret;
1584                 if (data_len < txreq.size) {
1585                         skb_shinfo(skb)->nr_frags++;
1586                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1587                                              pending_idx);
1588                 } else {
1589                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1590                                              INVALID_PENDING_IDX);
1591                 }
1592
1593                 netbk->pending_cons++;
1594
1595                 request_gop = xen_netbk_get_requests(netbk, vif,
1596                                                      skb, txfrags, gop);
1597                 if (request_gop == NULL) {
1598                         kfree_skb(skb);
1599                         netbk_tx_err(vif, &txreq, idx);
1600                         continue;
1601                 }
1602                 gop = request_gop;
1603
1604                 __skb_queue_tail(&netbk->tx_queue, skb);
1605
1606                 vif->tx.req_cons = idx;
1607                 xen_netbk_check_rx_xenvif(vif);
1608
1609                 if ((gop-netbk->tx_copy_ops) >= ARRAY_SIZE(netbk->tx_copy_ops))
1610                         break;
1611         }
1612
1613         return gop - netbk->tx_copy_ops;
1614 }
1615
1616 static void xen_netbk_tx_submit(struct xen_netbk *netbk)
1617 {
1618         struct gnttab_copy *gop = netbk->tx_copy_ops;
1619         struct sk_buff *skb;
1620
1621         while ((skb = __skb_dequeue(&netbk->tx_queue)) != NULL) {
1622                 struct xen_netif_tx_request *txp;
1623                 struct xenvif *vif;
1624                 u16 pending_idx;
1625                 unsigned data_len;
1626
1627                 pending_idx = *((u16 *)skb->data);
1628                 vif = netbk->pending_tx_info[pending_idx].vif;
1629                 txp = &netbk->pending_tx_info[pending_idx].req;
1630
1631                 /* Check the remap error code. */
1632                 if (unlikely(xen_netbk_tx_check_gop(netbk, skb, &gop))) {
1633                         netdev_dbg(vif->dev, "netback grant failed.\n");
1634                         skb_shinfo(skb)->nr_frags = 0;
1635                         kfree_skb(skb);
1636                         continue;
1637                 }
1638
1639                 data_len = skb->len;
1640                 memcpy(skb->data,
1641                        (void *)(idx_to_kaddr(netbk, pending_idx)|txp->offset),
1642                        data_len);
1643                 if (data_len < txp->size) {
1644                         /* Append the packet payload as a fragment. */
1645                         txp->offset += data_len;
1646                         txp->size -= data_len;
1647                 } else {
1648                         /* Schedule a response immediately. */
1649                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1650                 }
1651
1652                 if (txp->flags & XEN_NETTXF_csum_blank)
1653                         skb->ip_summed = CHECKSUM_PARTIAL;
1654                 else if (txp->flags & XEN_NETTXF_data_validated)
1655                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1656
1657                 xen_netbk_fill_frags(netbk, skb);
1658
1659                 /*
1660                  * If the initial fragment was < PKT_PROT_LEN then
1661                  * pull through some bytes from the other fragments to
1662                  * increase the linear region to PKT_PROT_LEN bytes.
1663                  */
1664                 if (skb_headlen(skb) < PKT_PROT_LEN && skb_is_nonlinear(skb)) {
1665                         int target = min_t(int, skb->len, PKT_PROT_LEN);
1666                         __pskb_pull_tail(skb, target - skb_headlen(skb));
1667                 }
1668
1669                 skb->dev      = vif->dev;
1670                 skb->protocol = eth_type_trans(skb, skb->dev);
1671                 skb_reset_network_header(skb);
1672
1673                 if (checksum_setup(vif, skb)) {
1674                         netdev_dbg(vif->dev,
1675                                    "Can't setup checksum in net_tx_action\n");
1676                         kfree_skb(skb);
1677                         continue;
1678                 }
1679
1680                 skb_probe_transport_header(skb, 0);
1681
1682                 vif->dev->stats.rx_bytes += skb->len;
1683                 vif->dev->stats.rx_packets++;
1684
1685                 xenvif_receive_skb(vif, skb);
1686         }
1687 }
1688
1689 /* Called after netfront has transmitted */
1690 static void xen_netbk_tx_action(struct xen_netbk *netbk)
1691 {
1692         unsigned nr_gops;
1693
1694         nr_gops = xen_netbk_tx_build_gops(netbk);
1695
1696         if (nr_gops == 0)
1697                 return;
1698
1699         gnttab_batch_copy(netbk->tx_copy_ops, nr_gops);
1700
1701         xen_netbk_tx_submit(netbk);
1702 }
1703
1704 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
1705                                   u8 status)
1706 {
1707         struct xenvif *vif;
1708         struct pending_tx_info *pending_tx_info;
1709         pending_ring_idx_t head;
1710         u16 peek; /* peek into next tx request */
1711
1712         BUG_ON(netbk->mmap_pages[pending_idx] == (void *)(~0UL));
1713
1714         /* Already complete? */
1715         if (netbk->mmap_pages[pending_idx] == NULL)
1716                 return;
1717
1718         pending_tx_info = &netbk->pending_tx_info[pending_idx];
1719
1720         vif = pending_tx_info->vif;
1721         head = pending_tx_info->head;
1722
1723         BUG_ON(!pending_tx_is_head(netbk, head));
1724         BUG_ON(netbk->pending_ring[pending_index(head)] != pending_idx);
1725
1726         do {
1727                 pending_ring_idx_t index;
1728                 pending_ring_idx_t idx = pending_index(head);
1729                 u16 info_idx = netbk->pending_ring[idx];
1730
1731                 pending_tx_info = &netbk->pending_tx_info[info_idx];
1732                 make_tx_response(vif, &pending_tx_info->req, status);
1733
1734                 /* Setting any number other than
1735                  * INVALID_PENDING_RING_IDX indicates this slot is
1736                  * starting a new packet / ending a previous packet.
1737                  */
1738                 pending_tx_info->head = 0;
1739
1740                 index = pending_index(netbk->pending_prod++);
1741                 netbk->pending_ring[index] = netbk->pending_ring[info_idx];
1742
1743                 xenvif_put(vif);
1744
1745                 peek = netbk->pending_ring[pending_index(++head)];
1746
1747         } while (!pending_tx_is_head(netbk, peek));
1748
1749         netbk->mmap_pages[pending_idx]->mapping = 0;
1750         put_page(netbk->mmap_pages[pending_idx]);
1751         netbk->mmap_pages[pending_idx] = NULL;
1752 }
1753
1754
1755 static void make_tx_response(struct xenvif *vif,
1756                              struct xen_netif_tx_request *txp,
1757                              s8       st)
1758 {
1759         RING_IDX i = vif->tx.rsp_prod_pvt;
1760         struct xen_netif_tx_response *resp;
1761         int notify;
1762
1763         resp = RING_GET_RESPONSE(&vif->tx, i);
1764         resp->id     = txp->id;
1765         resp->status = st;
1766
1767         if (txp->flags & XEN_NETTXF_extra_info)
1768                 RING_GET_RESPONSE(&vif->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1769
1770         vif->tx.rsp_prod_pvt = ++i;
1771         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->tx, notify);
1772         if (notify)
1773                 notify_remote_via_irq(vif->tx_irq);
1774 }
1775
1776 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
1777                                              u16      id,
1778                                              s8       st,
1779                                              u16      offset,
1780                                              u16      size,
1781                                              u16      flags)
1782 {
1783         RING_IDX i = vif->rx.rsp_prod_pvt;
1784         struct xen_netif_rx_response *resp;
1785
1786         resp = RING_GET_RESPONSE(&vif->rx, i);
1787         resp->offset     = offset;
1788         resp->flags      = flags;
1789         resp->id         = id;
1790         resp->status     = (s16)size;
1791         if (st < 0)
1792                 resp->status = (s16)st;
1793
1794         vif->rx.rsp_prod_pvt = ++i;
1795
1796         return resp;
1797 }
1798
1799 static inline int rx_work_todo(struct xen_netbk *netbk)
1800 {
1801         return !skb_queue_empty(&netbk->rx_queue);
1802 }
1803
1804 static inline int tx_work_todo(struct xen_netbk *netbk)
1805 {
1806
1807         if ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
1808              < MAX_PENDING_REQS) &&
1809              !list_empty(&netbk->net_schedule_list))
1810                 return 1;
1811
1812         return 0;
1813 }
1814
1815 static int xen_netbk_kthread(void *data)
1816 {
1817         struct xen_netbk *netbk = data;
1818         while (!kthread_should_stop()) {
1819                 wait_event_interruptible(netbk->wq,
1820                                 rx_work_todo(netbk) ||
1821                                 tx_work_todo(netbk) ||
1822                                 kthread_should_stop());
1823                 cond_resched();
1824
1825                 if (kthread_should_stop())
1826                         break;
1827
1828                 if (rx_work_todo(netbk))
1829                         xen_netbk_rx_action(netbk);
1830
1831                 if (tx_work_todo(netbk))
1832                         xen_netbk_tx_action(netbk);
1833         }
1834
1835         return 0;
1836 }
1837
1838 void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
1839 {
1840         if (vif->tx.sring)
1841                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1842                                         vif->tx.sring);
1843         if (vif->rx.sring)
1844                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1845                                         vif->rx.sring);
1846 }
1847
1848 int xen_netbk_map_frontend_rings(struct xenvif *vif,
1849                                  grant_ref_t tx_ring_ref,
1850                                  grant_ref_t rx_ring_ref)
1851 {
1852         void *addr;
1853         struct xen_netif_tx_sring *txs;
1854         struct xen_netif_rx_sring *rxs;
1855
1856         int err = -ENOMEM;
1857
1858         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1859                                      tx_ring_ref, &addr);
1860         if (err)
1861                 goto err;
1862
1863         txs = (struct xen_netif_tx_sring *)addr;
1864         BACK_RING_INIT(&vif->tx, txs, PAGE_SIZE);
1865
1866         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1867                                      rx_ring_ref, &addr);
1868         if (err)
1869                 goto err;
1870
1871         rxs = (struct xen_netif_rx_sring *)addr;
1872         BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
1873
1874         vif->rx_req_cons_peek = 0;
1875
1876         return 0;
1877
1878 err:
1879         xen_netbk_unmap_frontend_rings(vif);
1880         return err;
1881 }
1882
1883 static int __init netback_init(void)
1884 {
1885         int i;
1886         int rc = 0;
1887         int group;
1888
1889         if (!xen_domain())
1890                 return -ENODEV;
1891
1892         if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
1893                 pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
1894                         fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
1895                 fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
1896         }
1897
1898         xen_netbk_group_nr = num_online_cpus();
1899         xen_netbk = vzalloc(sizeof(struct xen_netbk) * xen_netbk_group_nr);
1900         if (!xen_netbk)
1901                 return -ENOMEM;
1902
1903         for (group = 0; group < xen_netbk_group_nr; group++) {
1904                 struct xen_netbk *netbk = &xen_netbk[group];
1905                 skb_queue_head_init(&netbk->rx_queue);
1906                 skb_queue_head_init(&netbk->tx_queue);
1907
1908                 init_timer(&netbk->net_timer);
1909                 netbk->net_timer.data = (unsigned long)netbk;
1910                 netbk->net_timer.function = xen_netbk_alarm;
1911
1912                 netbk->pending_cons = 0;
1913                 netbk->pending_prod = MAX_PENDING_REQS;
1914                 for (i = 0; i < MAX_PENDING_REQS; i++)
1915                         netbk->pending_ring[i] = i;
1916
1917                 init_waitqueue_head(&netbk->wq);
1918                 netbk->task = kthread_create(xen_netbk_kthread,
1919                                              (void *)netbk,
1920                                              "netback/%u", group);
1921
1922                 if (IS_ERR(netbk->task)) {
1923                         pr_alert("kthread_create() fails at netback\n");
1924                         del_timer(&netbk->net_timer);
1925                         rc = PTR_ERR(netbk->task);
1926                         goto failed_init;
1927                 }
1928
1929                 kthread_bind(netbk->task, group);
1930
1931                 INIT_LIST_HEAD(&netbk->net_schedule_list);
1932
1933                 spin_lock_init(&netbk->net_schedule_list_lock);
1934
1935                 atomic_set(&netbk->netfront_count, 0);
1936
1937                 wake_up_process(netbk->task);
1938         }
1939
1940         rc = xenvif_xenbus_init();
1941         if (rc)
1942                 goto failed_init;
1943
1944         return 0;
1945
1946 failed_init:
1947         while (--group >= 0) {
1948                 struct xen_netbk *netbk = &xen_netbk[group];
1949                 del_timer(&netbk->net_timer);
1950                 kthread_stop(netbk->task);
1951         }
1952         vfree(xen_netbk);
1953         return rc;
1954
1955 }
1956
1957 module_init(netback_init);
1958
1959 static void __exit netback_fini(void)
1960 {
1961         int i, j;
1962
1963         xenvif_xenbus_fini();
1964
1965         for (i = 0; i < xen_netbk_group_nr; i++) {
1966                 struct xen_netbk *netbk = &xen_netbk[i];
1967                 del_timer_sync(&netbk->net_timer);
1968                 kthread_stop(netbk->task);
1969                 for (j = 0; j < MAX_PENDING_REQS; j++) {
1970                         if (netbk->mmap_pages[j])
1971                                 __free_page(netbk->mmap_pages[j]);
1972                 }
1973         }
1974
1975         vfree(xen_netbk);
1976 }
1977 module_exit(netback_fini);
1978
1979 MODULE_LICENSE("Dual BSD/GPL");
1980 MODULE_ALIAS("xen-backend:vif");