From a3222f88fa4f2ebec4632aef527dd2c9a41b997d Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 11 Oct 2013 00:37:39 +0200 Subject: [PATCH] posix-timers: Remove dead task special case Now that we've removed all the optimizations that could result in NULL timer's targets, we can remove all the associated special case handling. Also add some warnings on NULL targets to spot any possible leftover. Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Oleg Nesterov Cc: Kosaki Motohiro Cc: Andrew Morton --- kernel/posix-cpu-timers.c | 70 ++++++++++++++------------------------- 1 file changed, 25 insertions(+), 45 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index dc4355b967db..ab9911b54faf 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -374,27 +374,27 @@ static int posix_cpu_timer_del(struct k_itimer *timer) struct task_struct *p = timer->it.cpu.task; int ret = 0; - if (likely(p != NULL)) { - read_lock(&tasklist_lock); - if (unlikely(p->sighand == 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 { - spin_lock(&p->sighand->siglock); - if (timer->it.cpu.firing) - ret = TIMER_RETRY; - else - list_del(&timer->it.cpu.entry); - spin_unlock(&p->sighand->siglock); - } - read_unlock(&tasklist_lock); + WARN_ON_ONCE(p == NULL); - if (!ret) - put_task_struct(p); + read_lock(&tasklist_lock); + if (unlikely(p->sighand == 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 { + spin_lock(&p->sighand->siglock); + if (timer->it.cpu.firing) + ret = TIMER_RETRY; + else + list_del(&timer->it.cpu.entry); + spin_unlock(&p->sighand->siglock); } + read_unlock(&tasklist_lock); + + if (!ret) + put_task_struct(p); return ret; } @@ -622,12 +622,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int flags, unsigned long long old_expires, new_expires, old_incr, val; int ret; - if (unlikely(p == NULL)) { - /* - * Timer refers to a dead task's clock. - */ - return -ESRCH; - } + WARN_ON_ONCE(p == NULL); new_expires = timespec_to_sample(timer->it_clock, &new->it_value); @@ -770,6 +765,8 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) unsigned long long now; struct task_struct *p = timer->it.cpu.task; + WARN_ON_ONCE(p == NULL); + /* * Easy part: convert the reload time. */ @@ -781,18 +778,6 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) return; } - if (unlikely(p == NULL)) { - WARN_ON_ONCE(CPUCLOCK_PERTHREAD(timer->it_clock)); - /* - * This task already died and the timer will never fire. - * In this case, expires is actually the dead value. - */ - dead: - sample_to_timespec(timer->it_clock, timer->it.cpu.expires, - &itp->it_value); - return; - } - /* * Sample the clock to take the difference with the expiry time. */ @@ -807,8 +792,9 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) * Call the timer disarmed, nothing else to do. */ timer->it.cpu.expires = 0; + sample_to_timespec(timer->it_clock, timer->it.cpu.expires, + &itp->it_value); read_unlock(&tasklist_lock); - goto dead; } else { cpu_timer_sample_group(timer->it_clock, p, &now); } @@ -1029,13 +1015,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) struct task_struct *p = timer->it.cpu.task; unsigned long long now; - if (unlikely(p == NULL)) { - WARN_ON_ONCE(CPUCLOCK_PERTHREAD(timer->it_clock)); - /* - * The task was cleaned up already, no future firings. - */ - goto out; - } + WARN_ON_ONCE(p == NULL); /* * Fetch the current sample and update the timer's expiry time. -- 2.20.1