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author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-09-22 14:42:48 -0700 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2008-09-24 15:45:48 +0200 |
commit | 36b2f046000b358b62b9d116cb10a2b1c5be5cbf (patch) | |
tree | 577f367d2408d6ed2618d49f412afa91bcb915e8 /kernel/posix-timers.c | |
parent | 2cd499e38ec241691e4bce50bddc8f57e4cc9bd0 (diff) | |
download | linux-36b2f046000b358b62b9d116cb10a2b1c5be5cbf.tar.gz linux-36b2f046000b358b62b9d116cb10a2b1c5be5cbf.tar.bz2 linux-36b2f046000b358b62b9d116cb10a2b1c5be5cbf.zip |
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 <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/posix-timers.c')
-rw-r--r-- | kernel/posix-timers.c | 23 |
1 files changed, 8 insertions, 15 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 60b262051d1d..5b761903b49a 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); |