[PATCH 1/1] cgroup: fix var may be used uninitialized warning

[PATCH 1/1] cgroup: fix var may be used uninitialized warning

[Javier Martinez Canillas]

When building cgroup, GCC warns that the root variable
may be used uninitialized in the cgroup_mount function.

kernel/cgroup.c: In function ‘cgroup_mount’:
kernel/cgroup.c:1886:13: warning: ‘root’ may be used uninitialized in this function [-Wuninitialized]
kernel/cgroup.c:1742:22: note: ‘root’ was declared here

This can never happen because if the struct cgroup_root
can't be allocated, ret is set to -ENOMEM and the error
returned so the code using root is not reachable. But
set root to NULL just to silence the compiler warning.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---

This patch is on top of today's linux-next (tag: next-20150303).

 kernel/cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 9a567836ee3a..bf1172d1c831 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1739,7 +1739,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 {
 	struct super_block *pinned_sb = NULL;
 	struct cgroup_subsys *ss;
-	struct cgroup_root *root;
+	struct cgroup_root *root = NULL;
 	struct cgroup_sb_opts opts;
 	struct dentry *dentry;
 	int ret;
-- 
2.1.3

Re: [PATCH 1/1] cgroup: fix var may be used uninitialized warning

[Tejun Heo]

On Tue, Mar 03, 2015 at 09:59:47AM +0100, Javier Martinez Canillas wrote:
> When building cgroup, GCC warns that the root variable
> may be used uninitialized in the cgroup_mount function.
> 
> kernel/cgroup.c: In function ‘cgroup_mount’:
> kernel/cgroup.c:1886:13: warning: ‘root’ may be used uninitialized in this function [-Wuninitialized]
> kernel/cgroup.c:1742:22: note: ‘root’ was declared here
> 
> This can never happen because if the struct cgroup_root
> can't be allocated, ret is set to -ENOMEM and the error
> returned so the code using root is not reachable. But
> set root to NULL just to silence the compiler warning.

Which compiler are you on?

Thanks.

-- 
tejun

Re: [PATCH 1/1] cgroup: fix var may be used uninitialized warning

[Javier Martinez Canillas]

Hello Tejun,

On 03/03/2015 02:46 PM, Tejun Heo wrote:
> On Tue, Mar 03, 2015 at 09:59:47AM +0100, Javier Martinez Canillas wrote:
>> When building cgroup, GCC warns that the root variable
>> may be used uninitialized in the cgroup_mount function.
>> 
>> kernel/cgroup.c: In function ‘cgroup_mount’:
>> kernel/cgroup.c:1886:13: warning: ‘root’ may be used uninitialized in this function [-Wuninitialized]
>> kernel/cgroup.c:1742:22: note: ‘root’ was declared here
>> 
>> This can never happen because if the struct cgroup_root
>> can't be allocated, ret is set to -ENOMEM and the error
>> returned so the code using root is not reachable. But
>> set root to NULL just to silence the compiler warning.
> 
> Which compiler are you on?
>

Yeah, I noticed that I was using a pretty old 4.7.2 GCC on
that machine and the warning indeed is not seen with 4.9.1.

Sorry for the noise...

> Thanks.
>

Best regard,
Javier