block: avoid using uninitialized value in from queue_var_store

As found by gcc-4.8, the QUEUE_SYSFS_BIT_FNS macro creates functions that use a value generated by queue_var_store independent of whether that value was set or not. block/blk-sysfs.c: In function 'queue_store_nonrot': block/blk-sysfs.c:244:385: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] Unlike most other such warnings, this one is not a false positive, writing any non-number string into the sysfs files indeed has an undefined result, rather than returning an error. Signed-off-by: Arnd Bergmann <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
nsekhar · Apr 3, 2013 · c678ef5 · c678ef5
1 parent 07961ac
commit c678ef5
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
@@ -229,6 +229,8 @@ queue_store_##name(struct request_queue *q, const char *page, size_t count) \
 	unsigned long val;						\
 	ssize_t ret;							\
 	ret = queue_var_store(&val, page, count);			\
+	if (ret < 0)							\
+		 return ret;						\
 	if (neg)							\
 		val = !val;						\
 									\