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>

2 files changed, 8 insertions, 8 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 7c0a3d9c9056..ae1ab6acf460 100644
--- 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 5ecda4ad8906..c071c3032700 100644
--- 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;
 };