From 800d4d30c8f20bd728e5741a3b77c4859a613f7c Mon Sep 17 00:00:00 2001 From: Yong Zhang Date: Sun, 20 Feb 2011 15:08:14 +0800 Subject: sched, autogroup: Stop going ahead if autogroup is disabled when autogroup is disable from the beginning, sched_autogroup_create_attach() autogroup_move_group() <== 1 sched_move_task() <== 2 task_move_group_fair() set_task_rq() task_group() autogroup_task_group() We go the whole path without doing anything useful. Then stop going further if autogroup is disabled. But there will be a race window between 1 and 2, in which sysctl_sched_autogroup_enabled is enabled. This issue will be toke by following patch. Signed-off-by: Yong Zhang Signed-off-by: Peter Zijlstra Cc: Mike Galbraith LKML-Reference: <1298185696-4403-4-git-send-email-yong.zhang0@gmail.com> Signed-off-by: Ingo Molnar --- kernel/sched_autogroup.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/sched_autogroup.c') diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c index 9fb65628315..137a096ae9d 100644 --- a/kernel/sched_autogroup.c +++ b/kernel/sched_autogroup.c @@ -161,11 +161,15 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag) p->signal->autogroup = autogroup_kref_get(ag); + if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled)) + goto out; + t = p; do { sched_move_task(t); } while_each_thread(p, t); +out: unlock_task_sighand(p, &flags); autogroup_kref_put(prev); } -- cgit v1.2.3-70-g09d2 From 511f67a5997c4967c69a3961e2fc9f04d8d244ac Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Tue, 22 Feb 2011 15:02:00 +0100 Subject: sched, autogroup: Stop claiming ownership of the root task group Disown it, and only display autogroup association if one exists. Signed-off-by: Mike Galbraith Reviewed-by: Yong Zhang Signed-off-by: Peter Zijlstra LKML-Reference: <1298383320.8036.5.camel@marge.simson.net> Signed-off-by: Ingo Molnar --- kernel/sched_autogroup.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel/sched_autogroup.c') diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c index 137a096ae9d..5946ac51560 100644 --- a/kernel/sched_autogroup.c +++ b/kernel/sched_autogroup.c @@ -12,7 +12,6 @@ static atomic_t autogroup_seq_nr; static void __init autogroup_init(struct task_struct *init_task) { autogroup_default.tg = &root_task_group; - root_task_group.autogroup = &autogroup_default; kref_init(&autogroup_default.kref); init_rwsem(&autogroup_default.lock); init_task->signal->autogroup = &autogroup_default; @@ -130,7 +129,7 @@ task_wants_autogroup(struct task_struct *p, struct task_group *tg) static inline bool task_group_is_autogroup(struct task_group *tg) { - return tg != &root_task_group && tg->autogroup; + return !!tg->autogroup; } static inline struct task_group * @@ -251,10 +250,14 @@ void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) { struct autogroup *ag = autogroup_task_get(p); + if (!task_group_is_autogroup(ag->tg)) + goto out; + down_read(&ag->lock); seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice); up_read(&ag->lock); +out: autogroup_kref_put(ag); } #endif /* CONFIG_PROC_FS */ @@ -262,9 +265,7 @@ void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) #ifdef CONFIG_SCHED_DEBUG static inline int autogroup_path(struct task_group *tg, char *buf, int buflen) { - int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); - - if (!enabled || !tg->autogroup) + if (!task_group_is_autogroup(tg)) return 0; return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); -- cgit v1.2.3-70-g09d2