[11/28] block: rdb: false-postive gcc-4.9 -Wmaybe-uninitialized
diff mbox

Message ID 20161017221037.1781185-2-arnd@arndb.de
State New
Headers show

Commit Message

Arnd Bergmann Oct. 17, 2016, 10:10 p.m. UTC
When building with gcc-4.9 -Wmaybe-uninitialized, we get a bogus
warning in rbd_watch_cb, as the variable is not used at all
in the one case in which it is not initialized first:

drivers/block/rbd.c: In function ‘rbd_watch_cb’:
drivers/block/rbd.c:3690:5: error: ‘struct_v’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/block/rbd.c:3759:5: note: ‘struct_v’ was declared here

Later compiler versions fix this, but adding another initialization
here is harmless and lets us build cleanly with 4.9 as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/block/rbd.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Ilya Dryomov Oct. 18, 2016, 9:57 a.m. UTC | #1
On Tue, Oct 18, 2016 at 12:10 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> When building with gcc-4.9 -Wmaybe-uninitialized, we get a bogus
> warning in rbd_watch_cb, as the variable is not used at all
> in the one case in which it is not initialized first:
>
> drivers/block/rbd.c: In function ‘rbd_watch_cb’:
> drivers/block/rbd.c:3690:5: error: ‘struct_v’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> drivers/block/rbd.c:3759:5: note: ‘struct_v’ was declared here
>
> Later compiler versions fix this, but adding another initialization
> here is harmless and lets us build cleanly with 4.9 as well.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/block/rbd.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index abb7162..4ab990b 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -3776,6 +3776,7 @@ static void rbd_watch_cb(void *arg, u64 notify_id, u64 cookie,
>         } else {
>                 /* legacy notification for header updates */
>                 notify_op = RBD_NOTIFY_OP_HEADER_UPDATE;
> +               struct_v = 0;
>                 len = 0;
>         }

It already got silenced by initializing at declaration in one of the
downstream trees, so I'd rather we do

@@ -3756,7 +3819,7 @@ static void rbd_watch_cb(void *arg, u64
notify_id, u64 cookie,
        struct rbd_device *rbd_dev = arg;
        void *p = data;
        void *const end = p + data_len;
-       u8 struct_v;
+       u8 struct_v = 0;
        u32 len;
        u32 notify_op;
        int ret;

to reduce the churn.

The "block" prefix is redundant and "rdb" should be "rbd" in the subject.

Thanks,

                Ilya
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Arnd Bergmann Oct. 18, 2016, 10:04 a.m. UTC | #2
On Tuesday, October 18, 2016 11:57:33 AM CEST Ilya Dryomov wrote:
> It already got silenced by initializing at declaration in one of the
> downstream trees, so I'd rather we do
> 
> @@ -3756,7 +3819,7 @@ static void rbd_watch_cb(void *arg, u64
> notify_id, u64 cookie,
>         struct rbd_device *rbd_dev = arg;
>         void *p = data;
>         void *const end = p + data_len;
> -       u8 struct_v;
> +       u8 struct_v = 0;
>         u32 len;
>         u32 notify_op;
>         int ret;
> 
> to reduce the churn.

Fair enough. I try to avoid adding extraneous initializations like
this, but my suggested change is not all that different here,
except if ceph_start_decoding() got changed in a way that could
lead to another uninitialized use.

> The "block" prefix is redundant and "rdb" should be "rbd" in the subject.

Oops.

	Arnd


--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index abb7162..4ab990b 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3776,6 +3776,7 @@  static void rbd_watch_cb(void *arg, u64 notify_id, u64 cookie,
 	} else {
 		/* legacy notification for header updates */
 		notify_op = RBD_NOTIFY_OP_HEADER_UPDATE;
+		struct_v = 0;
 		len = 0;
 	}