From d41d5a01631af821d3a3447e6613a316f5ee6c25 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 7 Feb 2011 17:02:20 +0100 Subject: [PATCH] cgroup: Fix cgroup_subsys::exit callback Make the ::exit method act like ::attach, it is after all very nearly the same thing. The bug had no effect on correctness - fixing it is an optimization for the scheduler. Also, later perf-cgroups patches rely on it. Signed-off-by: Peter Zijlstra Acked-by: Paul Menage LKML-Reference: <1297160655.13327.92.camel@laptop> Signed-off-by: Ingo Molnar --- include/linux/cgroup.h | 3 ++- kernel/cgroup.c | 31 ++++++++++++++++++------------- kernel/sched.c | 6 ++---- 3 files changed, 22 insertions(+), 18 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ce104e33cd22..38117d937332 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -474,7 +474,8 @@ struct cgroup_subsys { struct cgroup *old_cgrp, struct task_struct *tsk, bool threadgroup); void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); - void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); + void (*exit)(struct cgroup_subsys *ss, struct cgroup *cgrp, + struct cgroup *old_cgrp, struct task_struct *task); int (*populate)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b24d7027b83c..f6495f33a355 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4230,20 +4230,8 @@ void cgroup_post_fork(struct task_struct *child) */ void cgroup_exit(struct task_struct *tsk, int run_callbacks) { - int i; struct css_set *cg; - - if (run_callbacks && need_forkexit_callback) { - /* - * modular subsystems can't use callbacks, so no need to lock - * the subsys array - */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss->exit) - ss->exit(ss, tsk); - } - } + int i; /* * Unlink from the css_set task list if necessary. @@ -4261,7 +4249,24 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) task_lock(tsk); cg = tsk->cgroups; tsk->cgroups = &init_css_set; + + if (run_callbacks && need_forkexit_callback) { + /* + * modular subsystems can't use callbacks, so no need to lock + * the subsys array + */ + for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { + struct cgroup_subsys *ss = subsys[i]; + if (ss->exit) { + struct cgroup *old_cgrp = + rcu_dereference_raw(cg->subsys[i])->cgroup; + struct cgroup *cgrp = task_cgroup(tsk, i); + ss->exit(ss, cgrp, old_cgrp, tsk); + } + } + } task_unlock(tsk); + if (cg) put_css_set_taskexit(cg); } diff --git a/kernel/sched.c b/kernel/sched.c index e142e92f38da..79e611cd83dd 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -606,9 +606,6 @@ static inline struct task_group *task_group(struct task_struct *p) struct task_group *tg; struct cgroup_subsys_state *css; - if (p->flags & PF_EXITING) - return &root_task_group; - css = task_subsys_state_check(p, cpu_cgroup_subsys_id, lockdep_is_held(&task_rq(p)->lock)); tg = container_of(css, struct task_group, css); @@ -8863,7 +8860,8 @@ cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, } static void -cpu_cgroup_exit(struct cgroup_subsys *ss, struct task_struct *task) +cpu_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp, + struct cgroup *old_cgrp, struct task_struct *task) { /* * cgroup_exit() is called in the copy_process() failure path. -- 2.20.1