IB/srpt: Use a mutex to protect the channel list

In a later patch a function that can block will be called while
iterating over the rch_list. Hence protect that list with a
mutex instead of a spinlock. And since it is not allowed to sleep
while the task state != TASK_RUNNING, convert the list test in
srpt_ch_list_empty() into a lockless test.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Alex Estrin <alex.estrin@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index 0bf204e..33bd408 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -1862,12 +1862,11 @@ static void __srpt_close_ch(struct srpt_rdma_ch *ch)
  */
 static void srpt_close_ch(struct srpt_rdma_ch *ch)
 {
-       struct srpt_device *sdev;
+       struct srpt_device *sdev = ch->sport->sdev;
 
-       sdev = ch->sport->sdev;
-       spin_lock_irq(&sdev->spinlock);
+       mutex_lock(&sdev->mutex);
        __srpt_close_ch(ch);
-       spin_unlock_irq(&sdev->spinlock);
+       mutex_unlock(&sdev->mutex);
 }
 
 /**
@@ -1954,11 +1953,11 @@ static void srpt_release_channel_work(struct work_struct *w)
                             ch->sport->sdev, ch->rq_size,
                             ch->rsp_size, DMA_TO_DEVICE);
 
-       spin_lock_irq(&sdev->spinlock);
+       mutex_lock(&sdev->mutex);
        list_del_init(&ch->list);
        if (ch->release_done)
                complete(ch->release_done);
-       spin_unlock_irq(&sdev->spinlock);
+       mutex_unlock(&sdev->mutex);
 
        wake_up(&sdev->ch_releaseQ);
 
@@ -2039,7 +2038,7 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
        if ((req->req_flags & SRP_MTCH_ACTION) == SRP_MULTICHAN_SINGLE) {
                rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_NO_CHAN;
 
-               spin_lock_irq(&sdev->spinlock);
+               mutex_lock(&sdev->mutex);
 
                list_for_each_entry_safe(ch, tmp_ch, &sdev->rch_list, list) {
                        if (!memcmp(ch->i_port_id, req->initiator_port_id, 16)
@@ -2063,7 +2062,7 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
                        }
                }
 
-               spin_unlock_irq(&sdev->spinlock);
+               mutex_unlock(&sdev->mutex);
 
        } else
                rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_MAINTAINED;
@@ -2208,9 +2207,9 @@ try_again:
                goto release_channel;
        }
 
-       spin_lock_irq(&sdev->spinlock);
+       mutex_lock(&sdev->mutex);
        list_add_tail(&ch->list, &sdev->rch_list);
-       spin_unlock_irq(&sdev->spinlock);
+       mutex_unlock(&sdev->mutex);
 
        goto out;
 
@@ -2653,17 +2652,6 @@ static void srpt_refresh_port_work(struct work_struct *work)
        srpt_refresh_port(sport);
 }
 
-static int srpt_ch_list_empty(struct srpt_device *sdev)
-{
-       int res;
-
-       spin_lock_irq(&sdev->spinlock);
-       res = list_empty(&sdev->rch_list);
-       spin_unlock_irq(&sdev->spinlock);
-
-       return res;
-}
-
 /**
  * srpt_release_sdev() - Free the channel resources associated with a target.
  */
@@ -2676,13 +2664,13 @@ static int srpt_release_sdev(struct srpt_device *sdev)
 
        BUG_ON(!sdev);
 
-       spin_lock_irq(&sdev->spinlock);
+       mutex_lock(&sdev->mutex);
        list_for_each_entry_safe(ch, tmp_ch, &sdev->rch_list, list)
                __srpt_close_ch(ch);
-       spin_unlock_irq(&sdev->spinlock);
+       mutex_unlock(&sdev->mutex);
 
        res = wait_event_interruptible(sdev->ch_releaseQ,
-                                      srpt_ch_list_empty(sdev));
+                                      list_empty_careful(&sdev->rch_list));
        if (res)
                pr_err("%s: interrupted.\n", __func__);
 
@@ -2743,7 +2731,7 @@ static void srpt_add_one(struct ib_device *device)
        sdev->device = device;
        INIT_LIST_HEAD(&sdev->rch_list);
        init_waitqueue_head(&sdev->ch_releaseQ);
-       spin_lock_init(&sdev->spinlock);
+       mutex_init(&sdev->mutex);
 
        sdev->pd = ib_alloc_pd(device);
        if (IS_ERR(sdev->pd))
@@ -2971,12 +2959,12 @@ static void srpt_close_session(struct se_session *se_sess)
        pr_debug("ch %s-%d state %d\n", ch->sess_name, ch->qp->qp_num,
                 ch->state);
 
-       spin_lock_irq(&sdev->spinlock);
+       mutex_lock(&sdev->mutex);
        BUG_ON(ch->release_done);
        ch->release_done = &release_done;
        wait = !list_empty(&ch->list);
        __srpt_close_ch(ch);
-       spin_unlock_irq(&sdev->spinlock);
+       mutex_unlock(&sdev->mutex);
 
        if (!wait)
                return;

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h b/drivers/infiniband/ulp/srpt/ib_srpt.h
index 9c326c7..5883295 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -342,7 +342,7 @@ struct srpt_port {
  * @ioctx_ring:    Per-HCA SRQ.
  * @rch_list:      Per-device channel list -- see also srpt_rdma_ch.list.
  * @ch_releaseQ:   Enables waiting for removal from rch_list.
- * @spinlock:      Protects rch_list and tpg.
+ * @mutex:         Protects rch_list.
  * @port:          Information about the ports owned by this HCA.
  * @event_handler: Per-HCA asynchronous IB event handler.
  * @list:          Node in srpt_dev_list.
@@ -356,7 +356,7 @@ struct srpt_device {
        struct srpt_recv_ioctx  **ioctx_ring;
        struct list_head        rch_list;
        wait_queue_head_t       ch_releaseQ;
-       spinlock_t              spinlock;
+       struct mutex            mutex;
        struct srpt_port        port[2];
        struct ib_event_handler event_handler;
        struct list_head        list;