drivers/block/null_blk_main.c: fix uninitialized var warnings

With gcc-7.2, many instances of

drivers/block/null_blk_main.c: In function ‘nullb_device_zone_nr_conv_store’:
drivers/block/null_blk_main.c:291:12: warning: ‘new_value’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  dev->NAME = new_value;      \
            ^
drivers/block/null_blk_main.c:279:7: note: ‘new_value’ was declared here
  TYPE new_value;       \
       ^

Presumably notabug, so use uninitialized_var() to suppress them.

Cc: Shaohua Li <shli@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 9ce75f1..1651079 100644 (file)
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -276,7 +276,7 @@ nullb_device_##NAME##_store(struct config_item *item, const char *page,     \
 {                                                                      \
        int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;\
        struct nullb_device *dev = to_nullb_device(item);               \
-       TYPE new_value;                                                 \
+       TYPE uninitialized_var(new_value);                              \
        int ret;                                                        \
                                                                        \
        ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);\