From b182801ab35f7a0afb3cdf8ba5df464d04206b46 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 27 Apr 2011 21:56:14 +0200 Subject: signal: do_sigtimedwait() needs retarget_shared_pending() do_sigtimedwait() changes current->blocked and thus it needs set_current_blocked()->retarget_shared_pending(). We could use set_current_blocked() directly. It is fine to change ->real_blocked from all-zeroes to ->blocked and vice versa lockless, but this is not immediately clear, looks racy, and needs a huge comment to explain why this is correct. To keep the things simple this patch adds the new static helper, __set_task_blocked() which should be called with ->siglock held. This way we can change both ->real_blocked and ->blocked atomically under ->siglock as the current code does. This is more understandable. Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo Reviewed-by: Matt Fleming --- kernel/signal.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index 1ab89f677424..4d97e11d7672 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2299,6 +2299,18 @@ long do_no_restart_syscall(struct restart_block *param) return -EINTR; } +static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) +{ + if (signal_pending(tsk) && !thread_group_empty(tsk)) { + sigset_t newblocked; + /* A set of now blocked but previously unblocked signals. */ + signandsets(&newblocked, newset, ¤t->blocked); + retarget_shared_pending(tsk, &newblocked); + } + tsk->blocked = *newset; + recalc_sigpending(); +} + /** * set_current_blocked - change current->blocked mask * @newset: new mask @@ -2311,14 +2323,7 @@ void set_current_blocked(const sigset_t *newset) struct task_struct *tsk = current; spin_lock_irq(&tsk->sighand->siglock); - if (signal_pending(tsk) && !thread_group_empty(tsk)) { - sigset_t newblocked; - /* A set of now blocked but previously unblocked signals. */ - signandsets(&newblocked, newset, ¤t->blocked); - retarget_shared_pending(tsk, &newblocked); - } - tsk->blocked = *newset; - recalc_sigpending(); + __set_task_blocked(tsk, newset); spin_unlock_irq(&tsk->sighand->siglock); } @@ -2541,7 +2546,8 @@ int do_sigtimedwait(const sigset_t *which, siginfo_t *info, /* * None ready, temporarily unblock those we're interested * while we are sleeping in so that we'll be awakened when - * they arrive. + * they arrive. Unblocking is always fine, we can avoid + * set_current_blocked(). */ tsk->real_blocked = tsk->blocked; sigandsets(&tsk->blocked, &tsk->blocked, &mask); @@ -2551,10 +2557,9 @@ int do_sigtimedwait(const sigset_t *which, siginfo_t *info, timeout = schedule_timeout_interruptible(timeout); spin_lock_irq(&tsk->sighand->siglock); - sig = dequeue_signal(tsk, &mask, info); - tsk->blocked = tsk->real_blocked; + __set_task_blocked(tsk, &tsk->real_blocked); siginitset(&tsk->real_blocked, 0); - recalc_sigpending(); + sig = dequeue_signal(tsk, &mask, info); } spin_unlock_irq(&tsk->sighand->siglock); -- cgit v1.2.3-55-g7522