From 9465bee863bc4c6cf1566c12d6f92a8133e3da5c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 21 Oct 2005 15:36:00 -0700 Subject: [PATCH] Revert "Fix cpu timers exit deadlock and races" Revert commit e03d13e985d48ac4885382c9e3b1510c78bd047f, to be replaced by a much nicer fix from Roland. --- kernel/posix-cpu-timers.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index b3f3edc475d..7a51a5597c3 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -387,19 +387,25 @@ int posix_cpu_timer_del(struct k_itimer *timer) if (unlikely(p == NULL)) return 0; - spin_lock(&p->sighand->siglock); if (!list_empty(&timer->it.cpu.entry)) { - /* - * Take us off the task's timer list. We don't need to - * take tasklist_lock and check for the task being reaped. - * If it was reaped, it already called posix_cpu_timers_exit - * and posix_cpu_timers_exit_group to clear all the timers - * that pointed to it. - */ - list_del(&timer->it.cpu.entry); - put_task_struct(p); + read_lock(&tasklist_lock); + if (unlikely(p->signal == NULL)) { + /* + * We raced with the reaping of the task. + * The deletion should have cleared us off the list. + */ + BUG_ON(!list_empty(&timer->it.cpu.entry)); + } else { + /* + * Take us off the task's timer list. + */ + spin_lock(&p->sighand->siglock); + list_del(&timer->it.cpu.entry); + spin_unlock(&p->sighand->siglock); + } + read_unlock(&tasklist_lock); } - spin_unlock(&p->sighand->siglock); + put_task_struct(p); return 0; }