mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 08:19:28 +00:00
cgroup: release cgroup_mutex over file removals
Now that cftypes and all tree modification operations are protected by cgroup_tree_mutex, we can drop cgroup_mutex while deleting files and directories. Drop cgroup_mutex over removals. This doesn't make any noticeable difference now but is to help kernfs conversion. In kernfs, removals are sync points which drain in-flight operations as those operations would grab cgroup_mutex, trying to delete under cgroup_mutex would deadlock. This can be resolved by just holding the outer cgroup_tree_mutex which nests outside both kernfs active reference and cgroup_mutex. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
parent
ace2bee813
commit
4ac0601744
1 changed files with 10 additions and 5 deletions
|
@ -976,7 +976,9 @@ static int rebind_subsystems(struct cgroupfs_root *root,
|
|||
* Nothing can fail from this point on. Remove files for the
|
||||
* removed subsystems and rebind each subsystem.
|
||||
*/
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
cgroup_clear_dir(cgrp, removed_mask);
|
||||
mutex_lock(&cgroup_mutex);
|
||||
|
||||
for_each_subsys(ss, i) {
|
||||
unsigned long bit = 1UL << i;
|
||||
|
@ -2696,10 +2698,11 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
|
|||
u64 update_before;
|
||||
int ret = 0;
|
||||
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
|
||||
/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
|
||||
if (!cfts || ss->root == &cgroup_dummy_root ||
|
||||
!atomic_inc_not_zero(&sb->s_active)) {
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
mutex_unlock(&cgroup_tree_mutex);
|
||||
return 0;
|
||||
}
|
||||
|
@ -2723,18 +2726,15 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
|
|||
dput(prev);
|
||||
prev = cgrp->dentry;
|
||||
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
mutex_unlock(&cgroup_tree_mutex);
|
||||
mutex_lock(&inode->i_mutex);
|
||||
mutex_lock(&cgroup_tree_mutex);
|
||||
mutex_lock(&cgroup_mutex);
|
||||
if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
|
||||
ret = cgroup_addrm_files(cgrp, cfts, is_add);
|
||||
mutex_unlock(&inode->i_mutex);
|
||||
if (ret)
|
||||
break;
|
||||
}
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
mutex_unlock(&cgroup_tree_mutex);
|
||||
dput(prev);
|
||||
deactivate_super(sb);
|
||||
|
@ -4387,10 +4387,13 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
|
|||
/*
|
||||
* Initiate massacre of all css's. cgroup_destroy_css_killed()
|
||||
* will be invoked to perform the rest of destruction once the
|
||||
* percpu refs of all css's are confirmed to be killed.
|
||||
* percpu refs of all css's are confirmed to be killed. This
|
||||
* involves removing the subsystem's files, drop cgroup_mutex.
|
||||
*/
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
for_each_css(css, ssid, cgrp)
|
||||
kill_css(css);
|
||||
mutex_lock(&cgroup_mutex);
|
||||
|
||||
/*
|
||||
* Mark @cgrp dead. This prevents further task migration and child
|
||||
|
@ -4421,9 +4424,11 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
|
|||
* puts the base ref but we aren't quite done with @cgrp yet, so
|
||||
* hold onto it.
|
||||
*/
|
||||
mutex_unlock(&cgroup_mutex);
|
||||
cgroup_addrm_files(cgrp, cgroup_base_files, false);
|
||||
dget(d);
|
||||
cgroup_d_remove_dir(d);
|
||||
mutex_lock(&cgroup_mutex);
|
||||
|
||||
return 0;
|
||||
};
|
||||
|
|
Loading…
Reference in a new issue