[66/75] block: avoid using uninitialized value in fromqueue_var_store

From: Ben Hutchings
Date: Mon Apr 22 2013 - 10:29:59 EST


3.2.44-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>

commit c678ef5286ddb5cf70384ad5af286b0afc9b73e1 upstream.

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 <arnd@xxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
block/blk-sysfs.c | 2 ++
1 file changed, 2 insertions(+)

--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -200,6 +200,8 @@ queue_store_##name(struct request_queue
unsigned long val; \
ssize_t ret; \
ret = queue_var_store(&val, page, count); \
+ if (ret < 0) \
+ return ret; \
if (neg) \
val = !val; \
\

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