| Message ID | 1349448930-23976-8-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Oct 05, 2012 at 04:55:21PM +0200, Arnd Bergmann wrote: > In a configuration where the base cgroup support is enabled but > every single cgroup subsys is turned off, CGROUP_BUILTIN_SUBSYS_COUNT > is zero, which causes the sanity check code in cgroup_load_subsys > to trigger: > > BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); > BUG_ON(subsys[ss->subsys_id] != ss); > > Gcc first confirms that subsys_id cannot be 0 or larger and consequently > warns in the second line. > > kernel/cgroup.c: In function 'cgroup_load_subsys': > kernel/cgroup.c:4326:38: warning: array subscript is below array bounds [-Warray-bounds] > > Since the subsys_id can never be less than zero, we can just change the > type to an unsigned int, which makes the warning go away. > > Found by building ARM cns3420vb_defconfig. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Cc: Tejun Heo <tj@kernel.org> > Cc: Li Zefan <lizefan@huawei.com> > Cc: Ben Blum <bblum@andrew.cmu.edu> > --- > include/linux/cgroup.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index c90eaa8..26b99df 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -475,7 +475,7 @@ struct cgroup_subsys { > void (*post_clone)(struct cgroup *cgrp); > void (*bind)(struct cgroup *root); > > - int subsys_id; > + unsigned int subsys_id; > int active; > int disabled; > int early_init; > -- > 1.7.10 > > Oops. Thank you! Acked-by: Ben Blum <bblum@andrew.cmu.edu>
On Fri, Oct 05, 2012 at 04:55:21PM +0200, Arnd Bergmann wrote: > In a configuration where the base cgroup support is enabled but > every single cgroup subsys is turned off, CGROUP_BUILTIN_SUBSYS_COUNT > is zero, which causes the sanity check code in cgroup_load_subsys > to trigger: > > BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); > BUG_ON(subsys[ss->subsys_id] != ss); CGROUP_BUILTIN_SUBSYS_COUNT is already gone in mainline. I suppose this is no longer necessary? Thanks.
On Saturday 06 October 2012, Tejun Heo wrote: > On Fri, Oct 05, 2012 at 04:55:21PM +0200, Arnd Bergmann wrote: > > In a configuration where the base cgroup support is enabled but > > every single cgroup subsys is turned off, CGROUP_BUILTIN_SUBSYS_COUNT > > is zero, which causes the sanity check code in cgroup_load_subsys > > to trigger: > > > > BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); > > BUG_ON(subsys[ss->subsys_id] != ss); > > CGROUP_BUILTIN_SUBSYS_COUNT is already gone in mainline. I suppose > this is no longer necessary? Ah, you are right. I can confirm the problem is gone, and I'll drop the patch. Arnd
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c90eaa8..26b99df 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -475,7 +475,7 @@ struct cgroup_subsys { void (*post_clone)(struct cgroup *cgrp); void (*bind)(struct cgroup *root); - int subsys_id; + unsigned int subsys_id; int active; int disabled; int early_init;
In a configuration where the base cgroup support is enabled but every single cgroup subsys is turned off, CGROUP_BUILTIN_SUBSYS_COUNT is zero, which causes the sanity check code in cgroup_load_subsys to trigger: BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); BUG_ON(subsys[ss->subsys_id] != ss); Gcc first confirms that subsys_id cannot be 0 or larger and consequently warns in the second line. kernel/cgroup.c: In function 'cgroup_load_subsys': kernel/cgroup.c:4326:38: warning: array subscript is below array bounds [-Warray-bounds] Since the subsys_id can never be less than zero, we can just change the type to an unsigned int, which makes the warning go away. Found by building ARM cns3420vb_defconfig. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Ben Blum <bblum@andrew.cmu.edu> --- include/linux/cgroup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)