From 9e3bd6c3fb2334be171e69b432039cd18bce4458 Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Wed, 30 Apr 2008 00:52:41 -0700 Subject: [PATCH] signals: consolidate send_sigqueue and send_group_sigqueue Both functions do the same thing after proper locking, but with different sigpending structs, so move the common code into a helper. After this we have 4 places that look very similar: send_sigqueue: calls do_send_sigqueue and signal_wakeup send_group_sigqueue: calls do_send_sigqueue and __group_complete_signal __group_send_sig_info: calls send_signal and __group_complete_signal specific_send_sig_info: calls send_signal and signal_wakeup Besides, send_signal performs actions similar to do_send_sigqueue's and __group_complete_signal - to signal_wakeup. It looks like they can be consolidated gracefully. Oleg said: Personally, I think this change is very good. But send_sigqueue() and send_group_sigqueue() have a very subtle difference which I was never able to understand. Let's suppose that sigqueue is already queued, and the signal is ignored (the latter means we should re-schedule cpu timer or handle overrruns). In that case send_sigqueue() returns 0, but send_group_sigqueue() returns 1. I think this is not the problem (in fact, I think this patch makes the behaviour more correct), but I hope Thomas can take a look and confirm. Signed-off-by: Pavel Emelyanov Cc: Oleg Nesterov Cc: Roland McGrath Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/signal.c | 86 +++++++++++++++++-------------------------------- 1 file changed, 29 insertions(+), 57 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 6610a95506b..f9a52c72127 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1290,10 +1290,33 @@ void sigqueue_free(struct sigqueue *q) __sigqueue_free(q); } +static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t, + struct sigpending *pending) +{ + if (unlikely(!list_empty(&q->list))) { + /* + * If an SI_TIMER entry is already queue just increment + * the overrun count. + */ + + BUG_ON(q->info.si_code != SI_TIMER); + q->info.si_overrun++; + return 0; + } + + if (sig_ignored(t, sig)) + return 1; + + signalfd_notify(t, sig); + list_add_tail(&q->list, &pending->list); + sigaddset(&pending->signal, sig); + return 0; +} + int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) { unsigned long flags; - int ret = 0; + int ret = -1; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); @@ -1307,37 +1330,14 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) */ rcu_read_lock(); - if (!likely(lock_task_sighand(p, &flags))) { - ret = -1; + if (!likely(lock_task_sighand(p, &flags))) goto out_err; - } - if (unlikely(!list_empty(&q->list))) { - /* - * If an SI_TIMER entry is already queue just increment - * the overrun count. - */ - BUG_ON(q->info.si_code != SI_TIMER); - q->info.si_overrun++; - goto out; - } - /* Short-circuit ignored signals. */ - if (sig_ignored(p, sig)) { - ret = 1; - goto out; - } - /* - * Deliver the signal to listening signalfds. This must be called - * with the sighand lock held. - */ - signalfd_notify(p, sig); + ret = do_send_sigqueue(sig, q, p, &p->pending); - list_add_tail(&q->list, &p->pending.list); - sigaddset(&p->pending.signal, sig); if (!sigismember(&p->blocked, sig)) signal_wake_up(p, sig == SIGKILL); -out: unlock_task_sighand(p, &flags); out_err: rcu_read_unlock(); @@ -1349,7 +1349,7 @@ int send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) { unsigned long flags; - int ret = 0; + int ret; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); @@ -1358,38 +1358,10 @@ send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) spin_lock_irqsave(&p->sighand->siglock, flags); handle_stop_signal(sig, p); - /* Short-circuit ignored signals. */ - if (sig_ignored(p, sig)) { - ret = 1; - goto out; - } - - if (unlikely(!list_empty(&q->list))) { - /* - * If an SI_TIMER entry is already queue just increment - * the overrun count. Other uses should not try to - * send the signal multiple times. - */ - BUG_ON(q->info.si_code != SI_TIMER); - q->info.si_overrun++; - goto out; - } - /* - * Deliver the signal to listening signalfds. This must be called - * with the sighand lock held. - */ - signalfd_notify(p, sig); - - /* - * Put this signal on the shared-pending queue. - * We always use the shared queue for process-wide signals, - * to avoid several races. - */ - list_add_tail(&q->list, &p->signal->shared_pending.list); - sigaddset(&p->signal->shared_pending.signal, sig); + ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending); __group_complete_signal(sig, p); -out: + spin_unlock_irqrestore(&p->sighand->siglock, flags); read_unlock(&tasklist_lock); return ret; -- 2.46.0