From 2d42244ae71d6c7b0884b5664cf2eda30fb2ae68 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 20 Aug 2008 16:37:30 -0700 Subject: clocksource: introduce CLOCK_MONOTONIC_RAW In talking with Josip Loncaric, and his work on clock synchronization (see btime.sf.net), he mentioned that for really close synchronization, it is useful to have access to "hardware time", that is a notion of time that is not in any way adjusted by the clock slewing done to keep close time sync. Part of the issue is if we are using the kernel's ntp adjusted representation of time in order to measure how we should correct time, we can run into what Paul McKenney aptly described as "Painting a road using the lines we're painting as the guide". I had been thinking of a similar problem, and was trying to come up with a way to give users access to a purely hardware based time representation that avoided users having to know the underlying frequency and mask values needed to deal with the wide variety of possible underlying hardware counters. My solution is to introduce CLOCK_MONOTONIC_RAW. This exposes a nanosecond based time value, that increments starting at bootup and has no frequency adjustments made to it what so ever. The time is accessed from userspace via the posix_clock_gettime() syscall, passing CLOCK_MONOTONIC_RAW as the clock_id. Signed-off-by: John Stultz Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/posix-timers.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index e36d5798cbf..d3c66b53dff 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -222,6 +222,15 @@ static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp) return 0; } +/* + * Get monotonic time for posix timers + */ +static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp) +{ + getrawmonotonic(tp); + return 0; +} + /* * Initialize everything, well, just everything in Posix clocks/timers ;) */ @@ -235,9 +244,15 @@ static __init int init_posix_timers(void) .clock_get = posix_ktime_get_ts, .clock_set = do_posix_clock_nosettime, }; + struct k_clock clock_monotonic_raw = { + .clock_getres = hrtimer_get_res, + .clock_get = posix_get_monotonic_raw, + .clock_set = do_posix_clock_nosettime, + }; register_posix_clock(CLOCK_REALTIME, &clock_realtime); register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic); + register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw); posix_timers_cache = kmem_cache_create("posix_timers_cache", sizeof (struct k_itimer), 0, SLAB_PANIC, -- cgit v1.2.3-70-g09d2 From 4aa7361179bed905fd0f35b236a5c65db683b9e0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:46 -0700 Subject: posix-timers: don't switch to ->group_leader if ->it_process dies posix_timer_event() drops SIGEV_THREAD_ID and switches to ->group_leader if send_sigqueue() fails. This is not very useful and doesn't work reliably. send_sigqueue() can only fail if ->it_process is dead. But it can die before it dequeues the SI_TIMER signal, in that case the timer stops anyway. Remove this code. I guess it was needed a long ago to ensure that the timer is not destroyed when when its creator thread dies. Q: perhaps it makes sense to change sys_timer_settime() to return an error if ->it_process is dead? Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index e36d5798cbf..3dfd15aecc6 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -298,6 +298,7 @@ void do_schedule_next_timer(struct siginfo *info) int posix_timer_event(struct k_itimer *timr, int si_private) { + int shared, ret; /* * FIXME: if ->sigq is queued we can race with * dequeue_signal()->do_schedule_next_timer(). @@ -316,20 +317,10 @@ int posix_timer_event(struct k_itimer *timr, int si_private) timr->sigq->info.si_tid = timr->it_id; timr->sigq->info.si_value = timr->it_sigev_value; - if (timr->it_sigev_notify & SIGEV_THREAD_ID) { - struct task_struct *leader; - int ret = send_sigqueue(timr->sigq, timr->it_process, 0); - - if (likely(ret >= 0)) - return ret; - - timr->it_sigev_notify = SIGEV_SIGNAL; - leader = timr->it_process->group_leader; - put_task_struct(timr->it_process); - timr->it_process = leader; - } - - return send_sigqueue(timr->sigq, timr->it_process, 1); + shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); + ret = send_sigqueue(timr->sigq, timr->it_process, shared); + /* If we failed to send the signal the timer stops. */ + return ret > 0; } EXPORT_SYMBOL_GPL(posix_timer_event); -- cgit v1.2.3-70-g09d2 From 918fc0372831dca73039e1577bfea0c2ce49bdb6 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:46 -0700 Subject: posix-timers: always do get_task_struct(timer->it_process) Change the code to get/put timer->it_process regardless of SIGEV_THREAD_ID. This streamlines the create/destroy paths and allows us to simplify the usage of exit_itimers() in de_thread(). Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 3dfd15aecc6..bd9c931b365 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -540,11 +540,10 @@ sys_timer_create(const clockid_t which_clock, */ spin_lock_irqsave(&process->sighand->siglock, flags); if (!(process->flags & PF_EXITING)) { + get_task_struct(process); new_timer->it_process = process; list_add(&new_timer->list, &process->signal->posix_timers); - if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) - get_task_struct(process); spin_unlock_irqrestore(&process->sighand->siglock, flags); } else { spin_unlock_irqrestore(&process->sighand->siglock, flags); @@ -561,6 +560,7 @@ sys_timer_create(const clockid_t which_clock, new_timer->it_sigev_signo = SIGALRM; new_timer->it_sigev_value.sival_int = new_timer->it_id; process = current->group_leader; + get_task_struct(process); spin_lock_irqsave(&process->sighand->siglock, flags); new_timer->it_process = process; list_add(&new_timer->list, &process->signal->posix_timers); @@ -853,8 +853,7 @@ retry_delete: * This keeps any tasks waiting on the spin lock from thinking * they got something (see the lock code above). */ - if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) - put_task_struct(timer->it_process); + put_task_struct(timer->it_process); timer->it_process = NULL; unlock_timer(timer, flags); @@ -881,8 +880,7 @@ retry_delete: * This keeps any tasks waiting on the spin lock from thinking * they got something (see the lock code above). */ - if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) - put_task_struct(timer->it_process); + put_task_struct(timer->it_process); timer->it_process = NULL; unlock_timer(timer, flags); -- cgit v1.2.3-70-g09d2 From 2cd499e38ec241691e4bce50bddc8f57e4cc9bd0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:47 -0700 Subject: posix-timers: sys_timer_create: remove the buggy PF_EXITING check sys_timer_create() return -EINVAL if the target thread has PF_EXITING. This doesn't really make sense, the sub-thread can die right after unlock. And in fact, this is just wrong. Without SIGEV_THREAD_ID good_sigevent() returns ->group_leader, and it is very possible that the leader is already dead. This is OK, we shouldn't return the error in this case. Remove this check and the comment. Note that the "process" was found under tasklist_lock, it must have ->sighand != NULL. Also, remove a couple of unneeded initializations. Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 34 +++++++--------------------------- 1 file changed, 7 insertions(+), 27 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index bd9c931b365..60b262051d1 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -460,9 +460,9 @@ sys_timer_create(const clockid_t which_clock, timer_t __user * created_timer_id) { int error = 0; - struct k_itimer *new_timer = NULL; + struct k_itimer *new_timer; int new_timer_id; - struct task_struct *process = NULL; + struct task_struct *process; unsigned long flags; sigevent_t event; int it_id_set = IT_ID_NOT_SET; @@ -523,32 +523,12 @@ sys_timer_create(const clockid_t which_clock, read_lock(&tasklist_lock); if ((process = good_sigevent(&event))) { - /* - * We may be setting up this process for another - * thread. It may be exiting. To catch this - * case the we check the PF_EXITING flag. If - * the flag is not set, the siglock will catch - * him before it is too late (in exit_itimers). - * - * The exec case is a bit more invloved but easy - * to code. If the process is in our thread - * group (and it must be or we would not allow - * it here) and is doing an exec, it will cause - * us to be killed. In this case it will wait - * for us to die which means we can finish this - * linkage with our last gasp. I.e. no code :) - */ + get_task_struct(process); spin_lock_irqsave(&process->sighand->siglock, flags); - if (!(process->flags & PF_EXITING)) { - get_task_struct(process); - new_timer->it_process = process; - list_add(&new_timer->list, - &process->signal->posix_timers); - spin_unlock_irqrestore(&process->sighand->siglock, flags); - } else { - spin_unlock_irqrestore(&process->sighand->siglock, flags); - process = NULL; - } + new_timer->it_process = process; + list_add(&new_timer->list, + &process->signal->posix_timers); + spin_unlock_irqrestore(&process->sighand->siglock, flags); } read_unlock(&tasklist_lock); if (!process) { -- cgit v1.2.3-70-g09d2 From 36b2f046000b358b62b9d116cb10a2b1c5be5cbf Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:48 -0700 Subject: posix-timers: sys_timer_create: simplify and s/tasklist/rcu/ - Change the code to do rcu_read_lock() instead of taking tasklist_lock, it is safe to get_task_struct(p) if p was found under RCU. However, now we must not use process's sighand/signal, they may be NULL. We can use current->sighand/signal instead, this "process" must belong to the current's thread-group. - Factor out the common code for 2 "if (timer_event_spec)" branches, the !timer_event_spec case can use current too. - use spin_lock_irq() instead of _irqsave(), kill "flags". Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 60b262051d1..5b761903b49 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -463,7 +463,6 @@ sys_timer_create(const clockid_t which_clock, struct k_itimer *new_timer; int new_timer_id; struct task_struct *process; - unsigned long flags; sigevent_t event; int it_id_set = IT_ID_NOT_SET; @@ -521,16 +520,11 @@ sys_timer_create(const clockid_t which_clock, new_timer->it_sigev_signo = event.sigev_signo; new_timer->it_sigev_value = event.sigev_value; - read_lock(&tasklist_lock); - if ((process = good_sigevent(&event))) { + rcu_read_lock(); + process = good_sigevent(&event); + if (process) get_task_struct(process); - spin_lock_irqsave(&process->sighand->siglock, flags); - new_timer->it_process = process; - list_add(&new_timer->list, - &process->signal->posix_timers); - spin_unlock_irqrestore(&process->sighand->siglock, flags); - } - read_unlock(&tasklist_lock); + rcu_read_unlock(); if (!process) { error = -EINVAL; goto out; @@ -541,19 +535,18 @@ sys_timer_create(const clockid_t which_clock, new_timer->it_sigev_value.sival_int = new_timer->it_id; process = current->group_leader; get_task_struct(process); - spin_lock_irqsave(&process->sighand->siglock, flags); - new_timer->it_process = process; - list_add(&new_timer->list, &process->signal->posix_timers); - spin_unlock_irqrestore(&process->sighand->siglock, flags); } + spin_lock_irq(¤t->sighand->siglock); + new_timer->it_process = process; + list_add(&new_timer->list, ¤t->signal->posix_timers); + spin_unlock_irq(¤t->sighand->siglock); /* * In the case of the timer belonging to another task, after * the task is unlocked, the timer is owned by the other task * and may cease to exist at any time. Don't use or modify * new_timer after the unlock call. */ - out: if (error) release_posix_timer(new_timer, it_id_set); -- cgit v1.2.3-70-g09d2 From 717835d94d3e3d343a302df0a3cb9405887c3e2a Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:49 -0700 Subject: posix-timers: move the initialization of timer->sigq from send to create path posix_timer_event() always populates timer->sigq with the same numbers, move this code into sys_timer_create(). Note that with this patch we can kill it_sigev_signo and it_sigev_value. Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 5b761903b49..c459b29efdd 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -312,11 +312,6 @@ int posix_timer_event(struct k_itimer *timr, int si_private) */ timr->sigq->info.si_sys_private = si_private; - timr->sigq->info.si_signo = timr->it_sigev_signo; - timr->sigq->info.si_code = SI_TIMER; - timr->sigq->info.si_tid = timr->it_id; - timr->sigq->info.si_value = timr->it_sigev_value; - shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); ret = send_sigqueue(timr->sigq, timr->it_process, shared); /* If we failed to send the signal the timer stops. */ @@ -537,6 +532,11 @@ sys_timer_create(const clockid_t which_clock, get_task_struct(process); } + new_timer->sigq->info.si_code = SI_TIMER; + new_timer->sigq->info.si_tid = new_timer->it_id; + new_timer->sigq->info.si_signo = new_timer->it_sigev_signo; + new_timer->sigq->info.si_value = new_timer->it_sigev_value; + spin_lock_irq(¤t->sighand->siglock); new_timer->it_process = process; list_add(&new_timer->list, ¤t->signal->posix_timers); -- cgit v1.2.3-70-g09d2 From ef864c958801768fb28bd3603cd0b098b394671c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:49 -0700 Subject: posix-timers: sys_timer_create: cleanup the error handling Cleanup. - sys_timer_create() is big and complicated. The code above the "out:" label relies on the fact that "error" must be == 0. This is not very robust, make the code more explicit. Remove the unneeded initialization of error. - If idr_get_new() succeeds (as it normally should), we check the returned value twice. Move the "-EAGAIN" check under "if (error)". Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index c459b29efdd..7be385fe4ec 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -454,9 +454,8 @@ sys_timer_create(const clockid_t which_clock, struct sigevent __user *timer_event_spec, timer_t __user * created_timer_id) { - int error = 0; struct k_itimer *new_timer; - int new_timer_id; + int error, new_timer_id; struct task_struct *process; sigevent_t event; int it_id_set = IT_ID_NOT_SET; @@ -478,9 +477,9 @@ sys_timer_create(const clockid_t which_clock, error = idr_get_new(&posix_timers_id, (void *) new_timer, &new_timer_id); spin_unlock_irq(&idr_lock); - if (error == -EAGAIN) - goto retry; - else if (error) { + if (error) { + if (error == -EAGAIN) + goto retry; /* * Weird looking, but we return EAGAIN if the IDR is * full (proper POSIX return value for this) @@ -541,6 +540,8 @@ sys_timer_create(const clockid_t which_clock, new_timer->it_process = process; list_add(&new_timer->list, ¤t->signal->posix_timers); spin_unlock_irq(¤t->sighand->siglock); + + return 0; /* * In the case of the timer belonging to another task, after * the task is unlocked, the timer is owned by the other task @@ -548,9 +549,7 @@ sys_timer_create(const clockid_t which_clock, * new_timer after the unlock call. */ out: - if (error) - release_posix_timer(new_timer, it_id_set); - + release_posix_timer(new_timer, it_id_set); return error; } -- cgit v1.2.3-70-g09d2 From 5a9fa73072854981a5c05eb7ba18a96d49c2804f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:50 -0700 Subject: posix-timers: kill ->it_sigev_signo and ->it_sigev_value With the recent changes ->it_sigev_signo and ->it_sigev_value are only used in sys_timer_create(), kill them. Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- include/linux/posix-timers.h | 2 -- kernel/posix-timers.c | 17 +++++++---------- 2 files changed, 7 insertions(+), 12 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index f9d8e9e94e9..a7c72135554 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -45,8 +45,6 @@ struct k_itimer { int it_requeue_pending; /* waiting to requeue this timer */ #define REQUEUE_PENDING 1 int it_sigev_notify; /* notify word of sigevent struct */ - int it_sigev_signo; /* signo word of sigevent struct */ - sigval_t it_sigev_value; /* value word of sigevent struct */ struct task_struct *it_process; /* process to send signal to */ struct sigqueue *sigq; /* signal queue entry. */ union { diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 7be385fe4ec..3eff47b0d8d 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -510,10 +510,6 @@ sys_timer_create(const clockid_t which_clock, error = -EFAULT; goto out; } - new_timer->it_sigev_notify = event.sigev_notify; - new_timer->it_sigev_signo = event.sigev_signo; - new_timer->it_sigev_value = event.sigev_value; - rcu_read_lock(); process = good_sigevent(&event); if (process) @@ -524,17 +520,18 @@ sys_timer_create(const clockid_t which_clock, goto out; } } else { - new_timer->it_sigev_notify = SIGEV_SIGNAL; - new_timer->it_sigev_signo = SIGALRM; - new_timer->it_sigev_value.sival_int = new_timer->it_id; + event.sigev_notify = SIGEV_SIGNAL; + event.sigev_signo = SIGALRM; + event.sigev_value.sival_int = new_timer->it_id; process = current->group_leader; get_task_struct(process); } - new_timer->sigq->info.si_code = SI_TIMER; + new_timer->it_sigev_notify = event.sigev_notify; + new_timer->sigq->info.si_signo = event.sigev_signo; + new_timer->sigq->info.si_value = event.sigev_value; new_timer->sigq->info.si_tid = new_timer->it_id; - new_timer->sigq->info.si_signo = new_timer->it_sigev_signo; - new_timer->sigq->info.si_value = new_timer->it_sigev_value; + new_timer->sigq->info.si_code = SI_TIMER; spin_lock_irq(¤t->sighand->siglock); new_timer->it_process = process; -- cgit v1.2.3-70-g09d2 From 5a51b713ccf8835d5adf7217e2f86eb12b1ca851 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:51 -0700 Subject: posix-timers: lock_timer: kill the bogus ->it_id check lock_timer() checks that the timer found by idr_find(timer_id) has ->it_id == timer_id. This buys nothing. This check can fail only if sys_timer_create() unlocked idr_lock after idr_get_new(), but didn't set ->it_id = new_timer_id yet. But in that case ->it_process == NULL so lock_timer() can't succeed anyway. Also remove a couple of unneeded typecasts. Note that with or without this patch we have a small problem. sys_timer_create() doesn't ensure that the result of setting (say) ->it_sigev_notify must be visible if lock_timer() succeeds. Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 3eff47b0d8d..7185f05d53a 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -474,8 +474,7 @@ sys_timer_create(const clockid_t which_clock, goto out; } spin_lock_irq(&idr_lock); - error = idr_get_new(&posix_timers_id, (void *) new_timer, - &new_timer_id); + error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id); spin_unlock_irq(&idr_lock); if (error) { if (error == -EAGAIN) @@ -567,12 +566,12 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags) */ spin_lock_irqsave(&idr_lock, *flags); - timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id); + timr = idr_find(&posix_timers_id, (int) timer_id); if (timr) { spin_lock(&timr->it_lock); - if ((timr->it_id != timer_id) || !(timr->it_process) || - !same_thread_group(timr->it_process, current)) { + if (!timr->it_process || + !same_thread_group(timr->it_process, current)) { spin_unlock(&timr->it_lock); spin_unlock_irqrestore(&idr_lock, *flags); timr = NULL; -- cgit v1.2.3-70-g09d2 From 31d9284569e38fb97117497af3e8047a6a3c86f0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 22 Sep 2008 14:42:51 -0700 Subject: posix-timers: lock_timer: make it readable Cleanup. Imho makes the code much more understandable. At least this patch lessens both the source and compiled code. Signed-off-by: Oleg Nesterov Cc: mingo@elte.hu Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/posix-timers.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) (limited to 'kernel/posix-timers.c') diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 7185f05d53a..95451bf7d2e 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -556,7 +556,7 @@ out: * the find to the timer lock. To avoid a dead lock, the timer id MUST * be release with out holding the timer lock. */ -static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags) +static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags) { struct k_itimer *timr; /* @@ -564,23 +564,20 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags) * flags part over to the timer lock. Must not let interrupts in * while we are moving the lock. */ - spin_lock_irqsave(&idr_lock, *flags); - timr = idr_find(&posix_timers_id, (int) timer_id); + timr = idr_find(&posix_timers_id, (int)timer_id); if (timr) { spin_lock(&timr->it_lock); - - if (!timr->it_process || - !same_thread_group(timr->it_process, current)) { - spin_unlock(&timr->it_lock); - spin_unlock_irqrestore(&idr_lock, *flags); - timr = NULL; - } else + if (timr->it_process && + same_thread_group(timr->it_process, current)) { spin_unlock(&idr_lock); - } else - spin_unlock_irqrestore(&idr_lock, *flags); + return timr; + } + spin_unlock(&timr->it_lock); + } + spin_unlock_irqrestore(&idr_lock, *flags); - return timr; + return NULL; } /* -- cgit v1.2.3-70-g09d2