From 986094dfe161b4346831547136d4e5ed7f94310e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:54:51 -0800 Subject: [PATCH] exit: wait: drop tasklist_lock before psig->c* accounting wait_task_zombie() no longer needs tasklist_lock to accumulate the psig->c* counters, we can drop it right after cmpxchg(exit_state). Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: "Eric W. Biederman" Cc: Rik van Riel Cc: Sterling Alexander Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 457673d65934..6297eb0f5bd2 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1005,6 +1005,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) EXIT_TRACE : EXIT_DEAD; if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) return 0; + /* + * We own this thread, nobody else can reap it. + */ + read_unlock(&tasklist_lock); + sched_annotate_sleep(); /* * Check thread_group_leader() to exclude the traced sub-threads. @@ -1064,13 +1069,6 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) spin_unlock_irq(¤t->sighand->siglock); } - /* - * Now we are sure this task is interesting, and no other - * thread can reap it because we its state == DEAD/TRACE. - */ - read_unlock(&tasklist_lock); - sched_annotate_sleep(); - retval = wo->wo_rusage ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; status = (p->signal->flags & SIGNAL_GROUP_EXIT) -- 2.30.2