diff options
author | Tejun Heo | 2014-05-13 12:19:23 -0400 |
---|---|---|
committer | Tejun Heo | 2014-05-13 12:19:23 -0400 |
commit | e76ecaeef65c497153ceacf59c2e21c070d43f64 (patch) | |
tree | 5acc9ee3074440a3802526998ffdbd6fc0c2beff /kernel/cgroup.c | |
parent | a9746d8da786bc79b3b4ae1baa0fbbc4b795c1b7 (diff) |
cgroup: use cgroup_kn_lock_live() in other cgroup kernfs methods
Make __cgroup_procs_write() and cgroup_release_agent_write() use
cgroup_kn_lock_live() and cgroup_kn_unlock() instead of
cgroup_lock_live_group(). This puts the operations under both
cgroup_tree_mutex and cgroup_mutex protection without circular
dependency from kernfs active protection. Also, this means that
cgroup_mutex is no longer nested below kernfs active protection.
There is no longer any place where the two locks interact.
This leaves cgroup_lock_live_group() without any user. Removed.
This will help simplifying cgroup locking.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r-- | kernel/cgroup.c | 39 |
1 files changed, 12 insertions, 27 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 21739e481006..b7cd80845f6a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -386,23 +386,6 @@ static int notify_on_release(const struct cgroup *cgrp) ; \ else -/** - * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. - * @cgrp: the cgroup to be checked for liveness - * - * On success, returns true; the mutex should be later unlocked. On - * failure returns false with no lock held. - */ -static bool cgroup_lock_live_group(struct cgroup *cgrp) -{ - mutex_lock(&cgroup_mutex); - if (cgroup_is_dead(cgrp)) { - mutex_unlock(&cgroup_mutex); - return false; - } - return true; -} - /* the list of cgroups eligible for automatic release. Protected by * release_list_lock */ static LIST_HEAD(release_list); @@ -2306,14 +2289,15 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, { struct task_struct *tsk; const struct cred *cred = current_cred(), *tcred; - struct cgroup *cgrp = of_css(of)->cgroup; + struct cgroup *cgrp; pid_t pid; int ret; if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) return -EINVAL; - if (!cgroup_lock_live_group(cgrp)) + cgrp = cgroup_kn_lock_live(of->kn); + if (!cgrp) return -ENODEV; retry_find_task: @@ -2379,7 +2363,7 @@ retry_find_task: put_task_struct(tsk); out_unlock_cgroup: - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn); return ret ?: nbytes; } @@ -2429,17 +2413,18 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of, static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { - struct cgroup *cgrp = of_css(of)->cgroup; - struct cgroup_root *root = cgrp->root; + struct cgroup *cgrp; - BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX); - if (!cgroup_lock_live_group(cgrp)) + BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); + + cgrp = cgroup_kn_lock_live(of->kn); + if (!cgrp) return -ENODEV; spin_lock(&release_agent_path_lock); - strlcpy(root->release_agent_path, strstrip(buf), - sizeof(root->release_agent_path)); + strlcpy(cgrp->root->release_agent_path, strstrip(buf), + sizeof(cgrp->root->release_agent_path)); spin_unlock(&release_agent_path_lock); - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn); return nbytes; } |