Commit 78d4eb8a authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Jens Axboe

bcache: avoid clang -Wunintialized warning

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: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 4e0c04ec
...@@ -327,10 +327,11 @@ static int bch_allocator_thread(void *arg) ...@@ -327,10 +327,11 @@ static int bch_allocator_thread(void *arg)
* possibly issue discards to them, then we add the bucket to * possibly issue discards to them, then we add the bucket to
* the free list: * the free list:
*/ */
while (!fifo_empty(&ca->free_inc)) { while (1) {
long bucket; long bucket;
fifo_pop(&ca->free_inc, bucket); if (!fifo_pop(&ca->free_inc, bucket))
break;
if (ca->discard) { if (ca->discard) {
mutex_unlock(&ca->set->bucket_lock); mutex_unlock(&ca->set->bucket_lock);
......
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