[patch 21/21] mutex subsystem, semaphore to completion: drivers/block/loop.c

From: Ingo Molnar
Date: Thu Jan 05 2006 - 10:40:39 EST



convert the block loop device from semaphores to completions.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

----

drivers/block/loop.c | 27 ++++++++++++---------------
include/linux/loop.h | 4 ++--
2 files changed, 14 insertions(+), 17 deletions(-)

Index: linux/drivers/block/loop.c
===================================================================
--- linux.orig/drivers/block/loop.c
+++ linux/drivers/block/loop.c
@@ -514,12 +514,12 @@ static int loop_make_request(request_que
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;
@@ -580,23 +580,20 @@ 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);
@@ -619,7 +616,7 @@ static int loop_thread(void *data)
break;
}

- up(&lo->lo_sem);
+ complete(&lo->lo_done);
return 0;
}

@@ -830,7 +827,7 @@ static int loop_set_fd(struct loop_devic
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:
@@ -896,10 +893,10 @@ static int loop_clr_fd(struct loop_devic
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;

@@ -1276,8 +1273,8 @@ 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;
Index: linux/include/linux/loop.h
===================================================================
--- linux.orig/include/linux/loop.h
+++ linux/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;
-
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