| From 1ef36b0e7c77477b1d7f58fb12ed4532ba7d31a8 Mon Sep 17 00:00:00 2001 |
| From: Arnd Bergmann <arnd@arndb.de> |
| Date: Thu, 25 Apr 2019 00:48:28 +0800 |
| Subject: bcache: avoid clang -Wunintialized warning |
| |
| [ Upstream commit 78d4eb8ad9e1d413449d1b7a060f50b6efa81ebd ] |
| |
| clang has identified a code path in which it thinks a |
| variable may be unused: |
| |
| drivers/md/bcache/alloc.c:333:4: error: variable 'bucket' is used uninitialized whenever 'if' condition is false |
| [-Werror,-Wsometimes-uninitialized] |
| fifo_pop(&ca->free_inc, bucket); |
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop' |
| #define fifo_pop(fifo, i) fifo_pop_front(fifo, (i)) |
| ^~~~~~~~~~~~~~~~~~~~~~~~~ |
| drivers/md/bcache/util.h:189:6: note: expanded from macro 'fifo_pop_front' |
| if (_r) { \ |
| ^~ |
| drivers/md/bcache/alloc.c:343:46: note: uninitialized use occurs here |
| allocator_wait(ca, bch_allocator_push(ca, bucket)); |
| ^~~~~~ |
| drivers/md/bcache/alloc.c:287:7: note: expanded from macro 'allocator_wait' |
| if (cond) \ |
| ^~~~ |
| drivers/md/bcache/alloc.c:333:4: note: remove the 'if' if its condition is always true |
| fifo_pop(&ca->free_inc, bucket); |
| ^ |
| drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop' |
| #define fifo_pop(fifo, i) fifo_pop_front(fifo, (i)) |
| ^ |
| drivers/md/bcache/util.h:189:2: note: expanded from macro 'fifo_pop_front' |
| if (_r) { \ |
| ^ |
| drivers/md/bcache/alloc.c:331:15: note: initialize the variable 'bucket' to silence this warning |
| long bucket; |
| ^ |
| |
| This cannot happen in practice because we only enter the loop |
| if there is at least one element in the list. |
| |
| Slightly rearranging the code makes this clearer to both the |
| reader and the compiler, which avoids the warning. |
| |
| Signed-off-by: Arnd Bergmann <arnd@arndb.de> |
| Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> |
| Signed-off-by: Coly Li <colyli@suse.de> |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/md/bcache/alloc.c | 5 +++-- |
| 1 file changed, 3 insertions(+), 2 deletions(-) |
| |
| diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c |
| index 5002838ea4760..f8986effcb501 100644 |
| --- a/drivers/md/bcache/alloc.c |
| +++ b/drivers/md/bcache/alloc.c |
| @@ -327,10 +327,11 @@ static int bch_allocator_thread(void *arg) |
| * possibly issue discards to them, then we add the bucket to |
| * the free list: |
| */ |
| - while (!fifo_empty(&ca->free_inc)) { |
| + while (1) { |
| long bucket; |
| |
| - fifo_pop(&ca->free_inc, bucket); |
| + if (!fifo_pop(&ca->free_inc, bucket)) |
| + break; |
| |
| if (ca->discard) { |
| mutex_unlock(&ca->set->bucket_lock); |
| -- |
| 2.20.1 |
| |
