IB/srp: Change target_mutex to a spinlock

The SRP driver never sleeps while holding target_mutex, and it's just
used to protect some simple list operations, so hold times will be
short.  So just convert it to a spinlock, which is smaller and faster.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 7c0a3d9c9056fcadd6bf10b90e0039182dcc9236..ae1ab6acf460b93d06eef44ad5e4d1791a45fc3d 100644 (file)
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -361,9 +361,9 @@ static void srp_remove_work(void *target_ptr)
        target->state = SRP_TARGET_REMOVED;
        spin_unlock_irq(target->scsi_host->host_lock);
 
-       mutex_lock(&target->srp_host->target_mutex);
+       spin_lock(&target->srp_host->target_lock);
        list_del(&target->list);
-       mutex_unlock(&target->srp_host->target_mutex);
+       spin_unlock(&target->srp_host->target_lock);
 
        scsi_remove_host(target->scsi_host);
        ib_destroy_cm_id(target->cm_id);
@@ -1450,9 +1450,9 @@ static int srp_add_target(struct srp_host *host, struct srp_target_port *target)
        if (scsi_add_host(target->scsi_host, host->dev->dev->dma_device))
                return -ENODEV;
 
-       mutex_lock(&host->target_mutex);
+       spin_lock(&host->target_lock);
        list_add_tail(&target->list, &host->target_list);
-       mutex_unlock(&host->target_mutex);
+       spin_unlock(&host->target_lock);
 
        target->state = SRP_TARGET_LIVE;
 
@@ -1724,7 +1724,7 @@ static struct srp_host *srp_add_port(struct srp_device *device, u8 port)
                return NULL;
 
        INIT_LIST_HEAD(&host->target_list);
-       mutex_init(&host->target_mutex);
+       spin_lock_init(&host->target_lock);
        init_completion(&host->released);
        host->dev  = device;
        host->port = port;
@@ -1866,14 +1866,14 @@ static void srp_remove_one(struct ib_device *device)
                 * Mark all target ports as removed, so we stop queueing
                 * commands and don't try to reconnect.
                 */
-               mutex_lock(&host->target_mutex);
+               spin_lock(&host->target_lock);
                list_for_each_entry(target, &host->target_list, list) {
                        spin_lock_irqsave(target->scsi_host->host_lock, flags);
                        if (target->state != SRP_TARGET_REMOVED)
                                target->state = SRP_TARGET_REMOVED;
                        spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
                }
-               mutex_unlock(&host->target_mutex);
+               spin_unlock(&host->target_lock);
 
                /*
                 * Wait for any reconnection tasks that may have

diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 5ecda4ad8906bace194b1c20fb5d0795d1107b6c..c071c303270078dea305327da208c71060041889 100644 (file)
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -99,7 +99,7 @@ struct srp_host {
        u8                      port;
        struct class_device     class_dev;
        struct list_head        target_list;
-       struct mutex            target_mutex;
+       spinlock_t              target_lock;
        struct completion       released;
        struct list_head        list;
 };