[PATCH 2/3] don't take cgroup_mutex in destroy()
From: Glauber Costa <hidden>
Date: 2012-04-19 22:49:17
Also in:
cgroups
Subsystem:
block layer, control group - block io controller (blkio), the rest · Maintainers:
Jens Axboe, Tejun Heo, Josef Bacik, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2012-04-23 · Re: [PATCH 2/3] don't take cgroup_mutex in destroy() · Glauber Costa <hidden>
- 2012-04-21 · Re: [PATCH 2/3] don't take cgroup_mutex in destroy() · Li Zefan <hidden>
- 2012-04-20 · Re: [PATCH 2/3] don't take cgroup_mutex in destroy() · Glauber Costa <hidden>
- 2012-04-20 · Re: [PATCH 2/3] don't take cgroup_mutex in destroy() · Li Zefan <hidden>
- 2012-04-19 · Re: [PATCH 2/3] don't take cgroup_mutex in destroy() · Tejun Heo <hidden>
Most of the destroy functions are only doing very simple things like freeing memory. The ones who goes through lists and such, already use its own locking for those. * The cgroup itself won't go away until we free it, (after destroy) * The parent won't go away because we hold a reference count * There are no more tasks in the cgroup, and the cgroup is declared dead (cgroup_is_removed() == true) For the blk-cgroup and the cpusets, I got the impression that the mutex is still necessary. For those, I grabbed it from within the destroy function itself. If the maintainer for those subsystems consider it safe to remove it, we can discuss it separately. Signed-off-by: Glauber Costa <redacted> CC: Tejun Heo <redacted> CC: Li Zefan <redacted> CC: Kamezawa Hiroyuki <redacted> CC: Vivek Goyal <redacted> --- block/blk-cgroup.c | 2 ++ kernel/cgroup.c | 9 ++++----- kernel/cpuset.c | 2 ++ 3 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 126c341..477463f 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c@@ -1527,6 +1527,7 @@ static void blkiocg_destroy(struct cgroup *cgroup) struct blkio_policy_type *blkiop; struct blkio_policy_node *pn, *pntmp; + cgroup_lock(); rcu_read_lock(); do { spin_lock_irqsave(&blkcg->lock, flags);
@@ -1566,6 +1567,7 @@ static void blkiocg_destroy(struct cgroup *cgroup) rcu_read_unlock(); if (blkcg != &blkio_root_cgroup) kfree(blkcg); + cgroup_unlock(); } static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 932c318..976d332 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c@@ -869,13 +869,13 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) * agent */ synchronize_rcu(); - mutex_lock(&cgroup_mutex); /* * Release the subsystem state objects. */ for_each_subsys(cgrp->root, ss) ss->destroy(cgrp); + mutex_lock(&cgroup_mutex); cgrp->root->number_of_cgroups--; mutex_unlock(&cgroup_mutex);
@@ -3994,13 +3994,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, err_destroy: + mutex_unlock(&cgroup_mutex); for_each_subsys(root, ss) { if (cgrp->subsys[ss->subsys_id]) ss->destroy(cgrp); } - mutex_unlock(&cgroup_mutex); - /* Release the reference count that we took on the superblock */ deactivate_super(sb);
@@ -4349,9 +4348,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) int ret = cgroup_init_idr(ss, css); if (ret) { dummytop->subsys[ss->subsys_id] = NULL; + mutex_unlock(&cgroup_mutex); ss->destroy(dummytop); subsys[i] = NULL; - mutex_unlock(&cgroup_mutex); return ret; } }
@@ -4447,10 +4446,10 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) * pointer to find their state. note that this also takes care of * freeing the css_id. */ + mutex_unlock(&cgroup_mutex); ss->destroy(dummytop); dummytop->subsys[ss->subsys_id] = NULL; - mutex_unlock(&cgroup_mutex); } EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 8c8bd65..3cd4916 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c@@ -1862,10 +1862,12 @@ static void cpuset_destroy(struct cgroup *cont) { struct cpuset *cs = cgroup_cs(cont); + cgroup_lock(); if (is_sched_load_balance(cs)) update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); number_of_cpusets--; + cgroup_unlock(); free_cpumask_var(cs->cpus_allowed); kfree(cs); }
--
1.7.7.6