Maybe re-title this patch to BUG() if a bindable subsystem calls css_get() ?
Paul
On Fri, Oct 22, 2010 at 1:12 AM, Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
> For now bindable subsystems should not use css_get/put(), so warn
> on this misuse.
>
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> ---
> include/linux/cgroup.h | 7 +++++--
> kernel/cgroup.c | 3 +++
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 1e4e1df..10e4e02 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -80,13 +80,15 @@ struct cgroup_subsys_state {
>
> /* bits in struct cgroup_subsys_state flags field */
> enum {
> - CSS_ROOT, /* This CSS is the root of the subsystem */
> - CSS_REMOVED, /* This CSS is dead */
> + CSS_ROOT, /* This CSS is the root of the subsystem */
> + CSS_REMOVED, /* This CSS is dead */
> + CSS_NO_GET, /* Forbid calling css_get/put() */
> };
>
> /* Caller must verify that the css is not for root cgroup */
> static inline void __css_get(struct cgroup_subsys_state *css, int count)
> {
> + BUG_ON(test_bit(CSS_NO_GET, &css->flags));
> atomic_add(count, &css->refcnt);
> }
>
> @@ -119,6 +121,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
> {
> if (test_bit(CSS_ROOT, &css->flags))
> return true;
> + BUG_ON(test_bit(CSS_NO_GET, &css->flags));
> while (!atomic_inc_not_zero(&css->refcnt)) {
> if (test_bit(CSS_REMOVED, &css->flags))
> return false;
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 12c1f7c..88e265d 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -936,6 +936,9 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
> css->cgroup = cgrp;
> atomic_set(&css->refcnt, 1);
> css->flags = 0;
> + /* For now, a bindable subsystem should not call css_get/put(). */
> + if (ss->can_bind)
> + set_bit(CSS_NO_GET, &css->flags);
> css->id = NULL;
> if (cgrp == dummytop)
> set_bit(CSS_ROOT, &css->flags);
> --
> 1.7.0.1
>
>
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