[PATCH net-next] cgroup: fix sock_cgroup_data initialization on earlier compilers

[PATCH net-next] cgroup: fix sock_cgroup_data initialization on earlier compilers

[Tejun Heo]

sock_cgroup_data is a struct containing an anonymous union.
sock_cgroup_set_prioidx() and sock_cgroup_set_classid() were
initializing a field inside the anonymous union as follows.

 struct sock_ccgroup_data skcd_buf = { .val = VAL };

While this is fine on more recent compilers, gcc-4.4.7 triggers the
following errors.

 include/linux/cgroup-defs.h: In function ‘sock_cgroup_set_prioidx’:
 include/linux/cgroup-defs.h:619: error: unknown field ‘val’ specified in initializer
 include/linux/cgroup-defs.h:619: warning: missing braces around initializer
 include/linux/cgroup-defs.h:619: warning: (near initialization for ‘skcd_buf.<anonymous>’)

This is because .val belongs to the anonymous union nested inside the
struct but the initializer is missing the nesting.  Fix it by adding
an extra pair of braces.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Alaa Hleihel <alaa@dev.mellanox.co.il>
Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup")
---
 include/linux/cgroup-defs.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -616,7 +616,7 @@ static inline u32 sock_cgroup_classid(st
 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
 					   u16 prioidx)
 {
-	struct sock_cgroup_data skcd_buf = { .val = READ_ONCE(skcd->val) };
+	struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
 
 	if (sock_cgroup_prioidx(&skcd_buf) == prioidx)
 		return;
@@ -633,7 +633,7 @@ static inline void sock_cgroup_set_prioi
 static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
 					   u32 classid)
 {
-	struct sock_cgroup_data skcd_buf = { .val = READ_ONCE(skcd->val) };
+	struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
 
 	if (sock_cgroup_classid(&skcd_buf) == classid)
 		return;

Re: [PATCH net-next] cgroup: fix sock_cgroup_data initialization on earlier compilers

[David Miller]

From: Tejun Heo <tj@kernel.org>
Date: Wed, 9 Dec 2015 12:30:46 -0500

> sock_cgroup_data is a struct containing an anonymous union.
> sock_cgroup_set_prioidx() and sock_cgroup_set_classid() were
> initializing a field inside the anonymous union as follows.
> 
>  struct sock_ccgroup_data skcd_buf = { .val = VAL };
> 
> While this is fine on more recent compilers, gcc-4.4.7 triggers the
> following errors.
> 
>  include/linux/cgroup-defs.h: In function ‘sock_cgroup_set_prioidx’:
>  include/linux/cgroup-defs.h:619: error: unknown field ‘val’ specified in initializer
>  include/linux/cgroup-defs.h:619: warning: missing braces around initializer
>  include/linux/cgroup-defs.h:619: warning: (near initialization for ‘skcd_buf.<anonymous>’)
> 
> This is because .val belongs to the anonymous union nested inside the
> struct but the initializer is missing the nesting.  Fix it by adding
> an extra pair of braces.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Alaa Hleihel <alaa@dev.mellanox.co.il>
> Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup")

Applied, thanks.