From 6be96a5c905178637ec06a5d456a76b2b304fca3 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 6 Jun 2012 19:12:30 -0700 Subject: cgroup: remove hierarchy_mutex It was introduced for memcg to iterate cgroup hierarchy without holding cgroup_mutex, but soon after that it was replaced with a lockless way in memcg. No one used hierarchy_mutex since that, so remove it. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo --- kernel/cgroup.c | 45 --------------------------------------------- 1 file changed, 45 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ceeafe874b3..dec62f5936e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1073,28 +1073,24 @@ static int rebind_subsystems(struct cgroupfs_root *root, BUG_ON(cgrp->subsys[i]); BUG_ON(!dummytop->subsys[i]); BUG_ON(dummytop->subsys[i]->cgroup != dummytop); - mutex_lock(&ss->hierarchy_mutex); cgrp->subsys[i] = dummytop->subsys[i]; cgrp->subsys[i]->cgroup = cgrp; list_move(&ss->sibling, &root->subsys_list); ss->root = root; if (ss->bind) ss->bind(cgrp); - mutex_unlock(&ss->hierarchy_mutex); /* refcount was already taken, and we're keeping it */ } else if (bit & removed_bits) { /* We're removing this subsystem */ BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); BUG_ON(cgrp->subsys[i]->cgroup != cgrp); - mutex_lock(&ss->hierarchy_mutex); if (ss->bind) ss->bind(dummytop); dummytop->subsys[i]->cgroup = dummytop; cgrp->subsys[i] = NULL; subsys[i]->root = &rootnode; list_move(&ss->sibling, &rootnode.subsys_list); - mutex_unlock(&ss->hierarchy_mutex); /* subsystem is now free - drop reference on module */ module_put(ss->module); } else if (bit & final_bits) { @@ -3917,37 +3913,6 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, set_bit(CSS_CLEAR_CSS_REFS, &css->flags); } -static void cgroup_lock_hierarchy(struct cgroupfs_root *root) -{ - /* We need to take each hierarchy_mutex in a consistent order */ - int i; - - /* - * No worry about a race with rebind_subsystems that might mess up the - * locking order, since both parties are under cgroup_mutex. - */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss == NULL) - continue; - if (ss->root == root) - mutex_lock(&ss->hierarchy_mutex); - } -} - -static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) -{ - int i; - - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss == NULL) - continue; - if (ss->root == root) - mutex_unlock(&ss->hierarchy_mutex); - } -} - /* * cgroup_create - create a cgroup * @parent: cgroup that will be parent of the new cgroup @@ -4008,9 +3973,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, ss->post_clone(cgrp); } - cgroup_lock_hierarchy(root); list_add(&cgrp->sibling, &cgrp->parent->children); - cgroup_unlock_hierarchy(root); root->number_of_cgroups++; err = cgroup_create_dir(cgrp, dentry, mode); @@ -4037,9 +4000,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, err_remove: - cgroup_lock_hierarchy(root); list_del(&cgrp->sibling); - cgroup_unlock_hierarchy(root); root->number_of_cgroups--; err_destroy: @@ -4247,10 +4208,8 @@ again: list_del_init(&cgrp->release_list); raw_spin_unlock(&release_list_lock); - cgroup_lock_hierarchy(cgrp->root); /* delete this cgroup from parent->children */ list_del_init(&cgrp->sibling); - cgroup_unlock_hierarchy(cgrp->root); list_del_init(&cgrp->allcg_node); @@ -4324,8 +4283,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) * need to invoke fork callbacks here. */ BUG_ON(!list_empty(&init_task.tasks)); - mutex_init(&ss->hierarchy_mutex); - lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); ss->active = 1; /* this function shouldn't be used with modular subsystems, since they @@ -4452,8 +4409,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) } write_unlock(&css_set_lock); - mutex_init(&ss->hierarchy_mutex); - lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); ss->active = 1; /* success! */ -- cgit v1.2.3-70-g09d2 From ce27e317ba22b359bde02216afab934dac3af095 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 3 Jul 2012 10:38:06 -0700 Subject: cgroup: cgroup_rm_files() was calling simple_unlink() with the wrong inode While refactoring cgroup file removal path, 05ef1d7c4a "cgroup: introduce struct cfent" incorrectly changed the @dir argument of simple_unlink() to the inode of the file being deleted instead of that of the containing directory. The effect of this bug is minor - ctime and mtime of the parent weren't properly updated on file deletion. Fix it by using @cgrp->dentry->d_inode instead. Signed-off-by: Tejun Heo Reported-by: Al Viro Acked-by: Li Zefan Cc: stable@vger.kernel.org --- kernel/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index dec62f5936e..a56805aa0f1 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -959,7 +959,7 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) dget(d); d_delete(d); - simple_unlink(d->d_inode, d); + simple_unlink(cgrp->dentry->d_inode, d); list_del_init(&cfe->node); dput(d); -- cgit v1.2.3-70-g09d2