IB/srp: consolidate state change code
Bart Van Assche [Fri, 26 Nov 2010 18:13:06 +0000 (13:13 -0500)]
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ broken out and small cleanups by David Dillow ]
Signed-off-by: David Dillow <dillowda@ornl.gov>

drivers/infiniband/ulp/srp/ib_srp.c

index 29429a1..def9e6b 100644 (file)
@@ -441,18 +441,28 @@ static void srp_disconnect_target(struct srp_target_port *target)
        wait_for_completion(&target->done);
 }
 
+static bool srp_change_state(struct srp_target_port *target,
+                           enum srp_target_state old,
+                           enum srp_target_state new)
+{
+       bool changed = false;
+
+       spin_lock_irq(target->scsi_host->host_lock);
+       if (target->state == old) {
+               target->state = new;
+               changed = true;
+       }
+       spin_unlock_irq(target->scsi_host->host_lock);
+       return changed;
+}
+
 static void srp_remove_work(struct work_struct *work)
 {
        struct srp_target_port *target =
                container_of(work, struct srp_target_port, work);
 
-       spin_lock_irq(target->scsi_host->host_lock);
-       if (target->state != SRP_TARGET_DEAD) {
-               spin_unlock_irq(target->scsi_host->host_lock);
+       if (!srp_change_state(target, SRP_TARGET_DEAD, SRP_TARGET_REMOVED))
                return;
-       }
-       target->state = SRP_TARGET_REMOVED;
-       spin_unlock_irq(target->scsi_host->host_lock);
 
        spin_lock(&target->srp_host->target_lock);
        list_del(&target->list);
@@ -560,13 +570,8 @@ static int srp_reconnect_target(struct srp_target_port *target)
        struct ib_wc wc;
        int ret;
 
-       spin_lock_irq(target->scsi_host->host_lock);
-       if (target->state != SRP_TARGET_LIVE) {
-               spin_unlock_irq(target->scsi_host->host_lock);
+       if (!srp_change_state(target, SRP_TARGET_LIVE, SRP_TARGET_CONNECTING))
                return -EAGAIN;
-       }
-       target->state = SRP_TARGET_CONNECTING;
-       spin_unlock_irq(target->scsi_host->host_lock);
 
        srp_disconnect_target(target);
        /*
@@ -605,13 +610,8 @@ static int srp_reconnect_target(struct srp_target_port *target)
        if (ret)
                goto err;
 
-       spin_lock_irq(target->scsi_host->host_lock);
-       if (target->state == SRP_TARGET_CONNECTING) {
-               ret = 0;
-               target->state = SRP_TARGET_LIVE;
-       } else
+       if (!srp_change_state(target, SRP_TARGET_CONNECTING, SRP_TARGET_LIVE))
                ret = -EAGAIN;
-       spin_unlock_irq(target->scsi_host->host_lock);
 
        return ret;
 
@@ -621,9 +621,12 @@ err:
 
        /*
         * We couldn't reconnect, so kill our target port off.
-        * However, we have to defer the real removal because we might
-        * be in the context of the SCSI error handler now, which
-        * would deadlock if we call scsi_remove_host().
+        * However, we have to defer the real removal because we
+        * are in the context of the SCSI error handler now, which
+        * will deadlock if we call scsi_remove_host().
+        *
+        * Schedule our work inside the lock to avoid a race with
+        * the flush_scheduled_work() in srp_remove_one().
         */
        spin_lock_irq(target->scsi_host->host_lock);
        if (target->state == SRP_TARGET_CONNECTING) {