2 * net/tipc/log.c: TIPC print buffer routines for debugging
4 * Copyright (c) 1996-2006, Ericsson AB
5 * Copyright (c) 2005-2007, Wind River Systems
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9 * modification, are permitted provided that the following conditions are met:
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18 * this software without specific prior written permission.
20 * Alternatively, this software may be distributed under the terms of the
21 * GNU General Public License ("GPL") version 2 as published by the Free
22 * Software Foundation.
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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42 * TIPC pre-defines the following print buffers:
44 * TIPC_NULL : null buffer (i.e. print nowhere)
45 * TIPC_CONS : system console
46 * TIPC_LOG : TIPC log buffer
48 * Additional user-defined print buffers are also permitted.
50 static struct print_buf null_buf = { NULL, 0, NULL, 0 };
51 struct print_buf *const TIPC_NULL = &null_buf;
53 static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
54 struct print_buf *const TIPC_CONS = &cons_buf;
56 static struct print_buf log_buf = { NULL, 0, NULL, 1 };
57 struct print_buf *const TIPC_LOG = &log_buf;
60 * Locking policy when using print buffers.
62 * 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
63 * 'print_string' when writing to a print buffer. This also protects against
64 * concurrent writes to the print buffer being written to.
66 * 2) tipc_log_XXX() leverages the aforementioned use of 'print_lock' to
67 * protect against all types of concurrent operations on their associated
68 * print buffer (not just write operations).
70 * Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
71 * on the caller to prevent simultaneous use of the print buffer(s) being
74 static DEFINE_SPINLOCK(print_lock);
76 static void tipc_printbuf_move(struct print_buf *pb_to,
77 struct print_buf *pb_from);
80 * tipc_printbuf_init - initialize print buffer to empty
81 * @pb: pointer to print buffer structure
82 * @raw: pointer to character array used by print buffer
83 * @size: size of character array
85 * Note: If the character array is too small (or absent), the print buffer
86 * becomes a null device that discards anything written to it.
88 void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
95 if (size < TIPC_PB_MIN_SIZE) {
99 pb->buf[size - 1] = ~0;
104 * tipc_printbuf_reset - reinitialize print buffer to empty state
105 * @pb: pointer to print buffer structure
107 static void tipc_printbuf_reset(struct print_buf *pb)
112 pb->buf[pb->size - 1] = ~0;
117 * tipc_printbuf_empty - test if print buffer is in empty state
118 * @pb: pointer to print buffer structure
120 * Returns non-zero if print buffer is empty.
122 static int tipc_printbuf_empty(struct print_buf *pb)
124 return !pb->buf || (pb->crs == pb->buf);
128 * tipc_printbuf_move - move print buffer contents to another print buffer
129 * @pb_to: pointer to destination print buffer structure
130 * @pb_from: pointer to source print buffer structure
132 * Current contents of destination print buffer (if any) are discarded.
133 * Source print buffer becomes empty if a successful move occurs.
135 static void tipc_printbuf_move(struct print_buf *pb_to,
136 struct print_buf *pb_from)
140 /* Handle the cases where contents can't be moved */
145 tipc_printbuf_reset(pb_to);
149 if (pb_to->size < pb_from->size) {
150 strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
151 pb_to->buf[pb_to->size - 1] = ~0;
152 pb_to->crs = strchr(pb_to->buf, 0);
156 /* Copy data from char after cursor to end (if used) */
157 len = pb_from->buf + pb_from->size - pb_from->crs - 2;
158 if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
159 strcpy(pb_to->buf, pb_from->crs + 1);
160 pb_to->crs = pb_to->buf + len;
162 pb_to->crs = pb_to->buf;
164 /* Copy data from start to cursor (always) */
165 len = pb_from->crs - pb_from->buf;
166 strcpy(pb_to->crs, pb_from->buf);
169 tipc_printbuf_reset(pb_from);
173 * tipc_snprintf - append formatted output to print buffer
174 * @buf: pointer to print buffer
175 * @len: buffer length
176 * @fmt: formatted info to be printed
178 int tipc_snprintf(char *buf, int len, const char *fmt, ...)
184 i = vscnprintf(buf, len, fmt, args);
190 * tipc_log_resize - change the size of the TIPC log buffer
191 * @log_size: print buffer size to use
193 int tipc_log_resize(int log_size)
197 spin_lock_bh(&print_lock);
198 kfree(TIPC_LOG->buf);
199 TIPC_LOG->buf = NULL;
201 if (log_size < TIPC_PB_MIN_SIZE)
202 log_size = TIPC_PB_MIN_SIZE;
203 res = TIPC_LOG->echo;
204 tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
206 TIPC_LOG->echo = res;
207 res = !TIPC_LOG->buf;
209 spin_unlock_bh(&print_lock);
215 * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
217 struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
221 if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
222 return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
224 value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
226 return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
227 " (log size must be 0-32768)");
228 if (tipc_log_resize(value))
229 return tipc_cfg_reply_error_string(
230 "unable to create specified log (log size is now 0)");
231 return tipc_cfg_reply_none();
235 * tipc_log_dump - capture TIPC log buffer contents in configuration message
237 struct sk_buff *tipc_log_dump(void)
239 struct sk_buff *reply;
241 spin_lock_bh(&print_lock);
242 if (!TIPC_LOG->buf) {
243 spin_unlock_bh(&print_lock);
244 reply = tipc_cfg_reply_ultra_string("log not activated\n");
245 } else if (tipc_printbuf_empty(TIPC_LOG)) {
246 spin_unlock_bh(&print_lock);
247 reply = tipc_cfg_reply_ultra_string("log is empty\n");
249 struct tlv_desc *rep_tlv;
253 str_len = min(TIPC_LOG->size, 32768u);
254 spin_unlock_bh(&print_lock);
255 reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
257 rep_tlv = (struct tlv_desc *)reply->data;
258 tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
259 spin_lock_bh(&print_lock);
260 tipc_printbuf_move(&pb, TIPC_LOG);
261 spin_unlock_bh(&print_lock);
262 str_len = strlen(TLV_DATA(rep_tlv)) + 1;
263 skb_put(reply, TLV_SPACE(str_len));
264 TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);