Now that cgroup_unload_subsys() can tell whether the root css is
online or not, we can safely call cgroup_unload_subsys() after idr
init failure in cgroup_load_subsys().
Replace the manual unrolling and invoke cgroup_unload_subsys() on
failure. This drops cgroup_mutex inbetween but should be safe as the
subsystem will fail try_module_get() and thus can't be mounted
inbetween. As this means that cgroup_unload_subsys() can be called
before css_sets are rehashed, remove BUG_ON() on %NULL
css_set->subsys[] from cgroup_unload_subsys().
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
kernel/cgroup.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c3087f5..b42f63f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4400,8 +4400,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
*/
int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
{
- int i;
struct cgroup_subsys_state *css;
+ int i, ret;
/* check name and function validity */
if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
@@ -4452,15 +4452,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
init_cgroup_css(css, ss, dummytop);
/* init_idr must be after init_cgroup_css because it sets css->id. */
if (ss->use_id) {
- int ret = cgroup_init_idr(ss, css);
- if (ret) {
- ss->destroy(dummytop);
- dummytop->subsys[ss->subsys_id] = NULL;
- subsys[ss->subsys_id] = NULL;
- list_del_init(&ss->sibling);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
+ ret = cgroup_init_idr(ss, css);
+ if (ret)
+ goto err_unload;
}
/*
@@ -4498,6 +4492,12 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
/* success! */
mutex_unlock(&cgroup_mutex);
return 0;
+
+err_unload:
+ mutex_unlock(&cgroup_mutex);
+ /* @ss can't be mounted here as try_module_get() would fail */
+ cgroup_unload_subsys(ss);
+ return ret;
}
EXPORT_SYMBOL_GPL(cgroup_load_subsys);
@@ -4548,7 +4548,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
struct css_set *cg = link->cg;
hlist_del(&cg->hlist);
- BUG_ON(!cg->subsys[ss->subsys_id]);
cg->subsys[ss->subsys_id] = NULL;
hhead = css_set_hash(cg->subsys);
hlist_add_head(&cg->hlist, hhead);
--
1.7.11.7
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