[PATCH] mutex subsystem, semaphore to completion: drivers/block/loop.c

convert the block loop device from semaphores to completions.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 14 insertions, 17 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index bed9ad76c04c..864729046e22 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -527,12 +527,12 @@ static int loop_make_request(request_queue_t *q, struct bio *old_bio)
         lo->lo_pending++;
         loop_add_bio(lo, old_bio);
         spin_unlock_irq(&lo->lo_lock);
-        up(&lo->lo_bh_mutex);
+        complete(&lo->lo_bh_done);
         return 0;
 
 out:
         if (lo->lo_pending == 0)
-                up(&lo->lo_bh_mutex);
+                complete(&lo->lo_bh_done);
         spin_unlock_irq(&lo->lo_lock);
         bio_io_error(old_bio, old_bio->bi_size);
         return 0;
@@ -593,23 +593,20 @@ static int loop_thread(void *data)
         lo->lo_pending = 1;
 
         /*
-         * up sem, we are running
+         * complete it, we are running
          */
-        up(&lo->lo_sem);
+        complete(&lo->lo_done);
 
         for (;;) {
                 int pending;
 
-                /*
-                 * interruptible just to not contribute to load avg
-                 */
-                if (down_interruptible(&lo->lo_bh_mutex))
+                if (wait_for_completion_interruptible(&lo->lo_bh_done))
                         continue;
 
                 spin_lock_irq(&lo->lo_lock);
 
                 /*
-                 * could be upped because of tear-down, not pending work
+                 * could be completed because of tear-down, not pending work
                  */
                 if (unlikely(!lo->lo_pending)) {
                         spin_unlock_irq(&lo->lo_lock);
@@ -632,7 +629,7 @@ static int loop_thread(void *data)
                         break;
         }
 
-        up(&lo->lo_sem);
+        complete(&lo->lo_done);
         return 0;
 }
 
@@ -843,7 +840,7 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
         set_blocksize(bdev, lo_blocksize);
 
         kernel_thread(loop_thread, lo, CLONE_KERNEL);
-        down(&lo->lo_sem);
+        wait_for_completion(&lo->lo_done);
         return 0;
 
  out_putf:
@@ -909,10 +906,10 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
         lo->lo_state = Lo_rundown;
         lo->lo_pending--;
         if (!lo->lo_pending)
-                up(&lo->lo_bh_mutex);
+                complete(&lo->lo_bh_done);
         spin_unlock_irq(&lo->lo_lock);
 
-        down(&lo->lo_sem);
+        wait_for_completion(&lo->lo_done);
 
         lo->lo_backing_file = NULL;
 
@@ -1289,8 +1286,8 @@ static int __init loop_init(void)
                 if (!lo->lo_queue)
                         goto out_mem4;
                 init_MUTEX(&lo->lo_ctl_mutex);
-                init_MUTEX_LOCKED(&lo->lo_sem);
-                init_MUTEX_LOCKED(&lo->lo_bh_mutex);
+                init_completion(&lo->lo_done);
+                init_completion(&lo->lo_bh_done);
                 lo->lo_number = i;
                 spin_lock_init(&lo->lo_lock);
                 disk->major = LOOP_MAJOR;
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 40f63c9879d2..f96506782ebe 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -58,9 +58,9 @@ struct loop_device {
         struct bio              *lo_bio;
         struct bio              *lo_biotail;
         int                     lo_state;
-        struct semaphore        lo_sem;
+        struct completion       lo_done;
+        struct completion       lo_bh_done;
         struct semaphore        lo_ctl_mutex;
-        struct semaphore        lo_bh_mutex;
         int                     lo_pending;
 
         request_queue_t         *lo_queue;