[PATCH] dm: fix uninitialized variable reference

[PATCH] dm: fix uninitialized variable reference

[Arnd Bergmann]

The last bugfix apparently introduced another problem, as shown
by this gcc warning:

drivers/md/dm.c: In function '__send_changing_extent_only':
drivers/md/dm.c:1365:28: error: 'ti' is used uninitialized in this function [-Werror=uninitialized]

This restores the intialization of the 'ti' variable.

Fixes: aecefd4919de ("dm: fix __send_changing_extent_only() to send first bio and chain remainder")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I did not test this or give the patch much thought, this just seemed
to be the most likely fix I could come up with in a short time, so
please review carefully, and ignore if the solution is something
else.
---
 drivers/md/dm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 05aa9c094352..f19e9787076e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1356,6 +1356,10 @@ static int __send_changing_extent_only(struct clone_info *ci,
 	unsigned len;
 	unsigned num_bios;
 
+	ti = dm_table_find_target(ci->map, ci->sector);
+	if (!dm_target_is_valid(ti))
+		return -EIO;
+
 	/*
 	 * Even though the device advertised support for this type of
 	 * request, that does not mean every target supports it, and
-- 
2.9.0

Re: dm: fix uninitialized variable reference

[Mike Snitzer]

On Mon, Dec 11 2017 at  6:33am -0500,
Arnd Bergmann <arnd@arndb.de> wrote:

> The last bugfix apparently introduced another problem, as shown
> by this gcc warning:
> 
> drivers/md/dm.c: In function '__send_changing_extent_only':
> drivers/md/dm.c:1365:28: error: 'ti' is used uninitialized in this function [-Werror=uninitialized]
> 
> This restores the intialization of the 'ti' variable.
> 
> Fixes: aecefd4919de ("dm: fix __send_changing_extent_only() to send first bio and chain remainder")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> I did not test this or give the patch much thought, this just seemed
> to be the most likely fix I could come up with in a short time, so
> please review carefully, and ignore if the solution is something
> else.
> ---
>  drivers/md/dm.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 05aa9c094352..f19e9787076e 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1356,6 +1356,10 @@ static int __send_changing_extent_only(struct clone_info *ci,
>  	unsigned len;
>  	unsigned num_bios;
>  
> +	ti = dm_table_find_target(ci->map, ci->sector);
> +	if (!dm_target_is_valid(ti))
> +		return -EIO;
> +
>  	/*
>  	 * Even though the device advertised support for this type of
>  	 * request, that does not mean every target supports it, and
> -- 
> 2.9.0
> 

Already resolved this thanks to Stephen Rothwell's earlier
(substantially more discrete) mail.

I always enjoy a good public shaming but this cc list is particularly
wide.  Why?

Anyway, I resolved this differently:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.16&id=496cc64f4d10ba112aa0679a3bf29ae6ea74ff3d

Re: dm: fix uninitialized variable reference

[Arnd Bergmann]

On Mon, Dec 11, 2017 at 2:50 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Mon, Dec 11 2017 at  6:33am -0500,
> Arnd Bergmann <arnd@arndb.de> wrote:
>>
>
> Already resolved this thanks to Stephen Rothwell's earlier
> (substantially more discrete) mail.
>
> I always enjoy a good public shaming but this cc list is particularly
> wide.  Why?

;-)

Sorry about that, I just used the defaults that
scripts/get_maintainer.pl offered,
which is often easier than coming up with a smaller distribution list. You are
right this was a lot more than necessary in this case.

> Anyway, I resolved this differently:
> https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.16&id=496cc64f4d10ba112aa0679a3bf29ae6ea74ff3d

Ok, thanks!

      Arnd