From fe5fe90639b62a75349dd1f1c74c4a984397171c Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Fri, 12 Oct 2012 16:59:46 +0100 Subject: dm: use ACCESS_ONCE for sysfs values Use the ACCESS_ONCE macro in dm-bufio and dm-verity where a variable can be modified asynchronously (through sysfs) and we want to prevent compiler optimizations that assume that the variable hasn't changed. (See Documentation/atomic_ops.txt.) Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- drivers/md/dm-bufio.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'drivers/md/dm-bufio.c') diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index b9e006aa6062..651ca79881dd 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -280,9 +280,7 @@ static void __cache_size_refresh(void) BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); BUG_ON(dm_bufio_client_count < 0); - dm_bufio_cache_size_latch = dm_bufio_cache_size; - - barrier(); + dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size); /* * Use default if set to 0 and report the actual cache size used. @@ -812,7 +810,7 @@ static void __get_memory_limit(struct dm_bufio_client *c, { unsigned long buffers; - if (dm_bufio_cache_size != dm_bufio_cache_size_latch) { + if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) { mutex_lock(&dm_bufio_clients_lock); __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); @@ -1590,11 +1588,9 @@ EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); static void cleanup_old_buffers(void) { - unsigned long max_age = dm_bufio_max_age; + unsigned long max_age = ACCESS_ONCE(dm_bufio_max_age); struct dm_bufio_client *c; - barrier(); - if (max_age > ULONG_MAX / HZ) max_age = ULONG_MAX / HZ; -- cgit v1.2.3