On 12/12/2013 07:55 PM, Tejun Heo wrote:
> On Thu, Dec 12, 2013 at 10:35:36AM -0500, Tejun Heo wrote:
>> On Sat, Dec 07, 2013 at 11:58:05AM +0400, Vladimir Davydov wrote:
>>> We should not call cgroup_unload_subsys() if online_css() fails, because
>>> online_css() does not assign css to cgroup on failure, while
>>> offline_css() called from cgroup_unload_subsys() expects it is assigned.
>>> So let's call everything we need to rollback inline without involving
>>> cgroup_unload_subsys().
>>>
>>> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
>>> Cc: Tejun Heo <tj@xxxxxxxxxx>
>>> Cc: Li Zefan <lizefan@xxxxxxxxxx>
>> Applied to cgroup/for-3.13-fixes.
> Scrap that. I don't think we can fail css_online for the root css in
> 3.13-fixes and this would cause conflict with 3.14, so let's not
> commit it to 3.13-fixes. Vladimir, can you please respin the patch on
> top of cgroup/for-3.14
No problem.
> but make cgroup_unload_subsys() check whether
> css is actually there before calling offline so that it matches the
> usual offline path better?
You want me to add something like this to the patch, don't you?
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 402f7aa..bc03b97 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4680,6 +4680,7 @@ EXPORT_SYMBOL_GPL(cgroup_load_subsys);
void cgroup_unload_subsys(struct cgroup_subsys *ss)
{
struct cgrp_cset_link *link;
+ struct cgroup_subsys_state *css;
BUG_ON(ss->module == NULL);
@@ -4693,7 +4694,9 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
mutex_lock(&cgroup_mutex);
mutex_lock(&cgroup_root_mutex);
- offline_css(cgroup_css(cgroup_dummy_top, ss));
+ css = cgroup_css(cgroup_dummy_top, ss);
+ if (css)
+ offline_css(css);
/* deassign the subsys_id */
cgroup_subsys[ss->subsys_id] = NULL;
If so, I don't mind, but why? cgroup_unload_subsys() should never be
called without properly initialized css.
Thanks.
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