From c0f6fa8c409fc7fe63bfd0a57efad29dec262bcb Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Tue, 23 Nov 2010 21:37:03 -0800 Subject: cgroup: Set CGRP_RELEASABLE when adding to a cgroup Changes the meaning of CGRP_RELEASABLE to be set on any cgroup that has ever had a task or cgroup in it, or had css_get called on it. The bit is set in cgroup_attach_task, cgroup_create, and __css_get. It is not necessary to set the bit in cgroup_fork, as the task is either in the root cgroup, in which can never be released, or the task it was forked from already set the bit in croup_attach_task. Signed-off-by: Colin Cross --- kernel/cgroup.c | 53 +++++++++++++++++++++++------------------------------ 1 file changed, 23 insertions(+), 30 deletions(-) (limited to 'kernel/cgroup.c') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ed64ccac67c..0de816098bf 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -352,7 +352,15 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) * compiled into their kernel but not actually in use */ static int use_task_css_set_links __read_mostly; -static void __put_css_set(struct css_set *cg, int taskexit) +/* + * refcounted get/put for css_set objects + */ +static inline void get_css_set(struct css_set *cg) +{ + atomic_inc(&cg->refcount); +} + +static void put_css_set(struct css_set *cg) { struct cg_cgroup_link *link; struct cg_cgroup_link *saved_link; @@ -378,12 +386,8 @@ static void __put_css_set(struct css_set *cg, int taskexit) struct cgroup *cgrp = link->cgrp; list_del(&link->cg_link_list); list_del(&link->cgrp_link_list); - if (atomic_dec_and_test(&cgrp->count) && - notify_on_release(cgrp)) { - if (taskexit) - set_bit(CGRP_RELEASABLE, &cgrp->flags); + if (atomic_dec_and_test(&cgrp->count)) check_for_release(cgrp); - } kfree(link); } @@ -392,24 +396,6 @@ static void __put_css_set(struct css_set *cg, int taskexit) kfree_rcu(cg, rcu_head); } -/* - * refcounted get/put for css_set objects - */ -static inline void get_css_set(struct css_set *cg) -{ - atomic_inc(&cg->refcount); -} - -static inline void put_css_set(struct css_set *cg) -{ - __put_css_set(cg, 0); -} - -static inline void put_css_set_taskexit(struct css_set *cg) -{ - __put_css_set(cg, 1); -} - /* * compare_css_sets - helper function for find_existing_css_set(). * @cg: candidate css_set being tested @@ -1931,6 +1917,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) ss->attach(cgrp, &tset); } + set_bit(CGRP_RELEASABLE, &cgrp->flags); synchronize_rcu(); /* @@ -3784,6 +3771,8 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (err < 0) goto err_remove; + set_bit(CGRP_RELEASABLE, &parent->flags); + /* The cgroup directory was pre-locked for us */ BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); @@ -4000,7 +3989,6 @@ again: cgroup_d_remove_dir(d); dput(d); - set_bit(CGRP_RELEASABLE, &parent->flags); check_for_release(parent); /* @@ -4631,7 +4619,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) task_unlock(tsk); if (cg) - put_css_set_taskexit(cg); + put_css_set(cg); } /** @@ -4684,6 +4672,14 @@ static void check_for_release(struct cgroup *cgrp) } } +/* Caller must verify that the css is not for root cgroup */ +void __css_get(struct cgroup_subsys_state *css, int count) +{ + atomic_add(count, &css->refcnt); + set_bit(CGRP_RELEASABLE, &css->cgroup->flags); +} +EXPORT_SYMBOL_GPL(__css_get); + /* Caller must verify that the css is not for root cgroup */ void __css_put(struct cgroup_subsys_state *css, int count) { @@ -4692,10 +4688,7 @@ void __css_put(struct cgroup_subsys_state *css, int count) rcu_read_lock(); val = atomic_sub_return(count, &css->refcnt); if (val == 1) { - if (notify_on_release(cgrp)) { - set_bit(CGRP_RELEASABLE, &cgrp->flags); - check_for_release(cgrp); - } + check_for_release(cgrp); cgroup_wakeup_rmdir_waiter(cgrp); } rcu_read_unlock(); -- cgit v1.2.3