From nobody Mon Nov 25 04:00:09 2024 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E0DC1BD515 for ; Thu, 31 Oct 2024 15:46:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730389599; cv=none; b=D3XeqcAc5qbd1KuvOdngmTa3STIw6edpDSIoVmtWUOMKcJd4PwTuKg6yHsIoChAlKnK517EL85IZ9ttnJPhxH0YGo5A3A1eL7xNiYP6qzcugi7lDoXGs+d4aG/JK7+9XyXWQmlBgDJv/PQQnhjYScGg06GZvrBbpyFRUHZlTcAo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730389599; c=relaxed/simple; bh=CexgufO+1Osh5TMOL66HRJxKyFDyiRssUXwnxU9QZ7A=; h=Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type:Date; b=MJlEE96/946HhJQkaDNpQY6IPNeMXXS4YwMCdzQCl0TKmUACIjR+AAbs/ihUiyKruSTnVTh8CEpP1TWh0/yMMvJeY3V1E5tlchipf/x6X7h2wQkl9YfpGhgLaDzvRe194Z0F+SnMkjcdnMw+IBiAkALb7OQ1guD0Z0s7ltjd22k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=GRxH1ijY; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=o9QnRikO; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="GRxH1ijY"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="o9QnRikO" Message-ID: <20241031154425.119202459@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1730389594; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ChIynh12PYnBXnJ3TWILE4o90Tsj+76TEesTqrWpYsU=; b=GRxH1ijYp8N1NtIJU+yFpPeI7GWAjrUJ/LA6m0sanotdE1tectOHaWYmyD2HAySlmZtvUl 7BjxXP3C/aillEvm7WYZoYVM8gVde2S8IeF1IJzNV+OE/bi8hKjVHHPhtEg3T0a0z1lsXA hi0+clRIbKWF0tzF8liNuxvuY+kIBK4lv+kDACyQ1/nBj3GvZzu422CnHdM5DrF0sRi2m8 n3JIegp7bYiiLWhyC8KQnZUD3ZEAjBy6BHFyLj/yAurUbNwWy9A801FP3M0Afg9gCJDauM osp5efm9U6m28PFgUO1bpiQqLA6FkGg5Gva6Ja9I3sj935QwdxyltLpYbr/85Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1730389594; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ChIynh12PYnBXnJ3TWILE4o90Tsj+76TEesTqrWpYsU=; b=o9QnRikOMkaxkTGjXEaAzzFFmGXW/0IpSuGeLe9T3n/DPcucqwc+fjSpQdLOFPDFTnVWxQ FyOUe2EkZpFeLDAw== From: Thomas Gleixner To: LKML Cc: Anna-Maria Behnsen , Frederic Weisbecker , John Stultz , Peter Zijlstra , Ingo Molnar , Stephen Boyd , Eric Biederman , Oleg Nesterov Subject: [patch v6 09/20] signal: Refactor send_sigqueue() References: <20241031151625.361697424@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Thu, 31 Oct 2024 16:46:34 +0100 (CET) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To handle posix timers which have their signal ignored via SIG_IGN properly it is required to requeue a ignored signal for delivery when SIG_IGN is lifted so the timer gets rearmed. Split the required code out of send_sigqueue() so it can be reused in context of sigaction(). While at it rename send_sigqueue() to posixtimer_send_sigqueue() so its clear what this is about. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) --- include/linux/posix-timers.h | 1=20 include/linux/sched/signal.h | 1=20 kernel/signal.c | 82 +++++++++++++++++++++++---------------= ----- kernel/time/posix-timers.c | 2 - 4 files changed, 47 insertions(+), 39 deletions(-) --- --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -109,6 +109,7 @@ static inline void posix_cputimers_rt_wa =20 void posixtimer_rearm_itimer(struct task_struct *p); bool posixtimer_init_sigqueue(struct sigqueue *q); +int posixtimer_send_sigqueue(struct k_itimer *tmr); bool posixtimer_deliver_signal(struct kernel_siginfo *info); void posixtimer_free_timer(struct k_itimer *timer); =20 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -340,7 +340,6 @@ extern int send_sig(int, struct task_str extern int zap_other_threads(struct task_struct *p); extern struct sigqueue *sigqueue_alloc(void); extern void sigqueue_free(struct sigqueue *); -extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type, i= nt si_private); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); =20 static inline void clear_notify_signal(void) --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1947,40 +1947,54 @@ void sigqueue_free(struct sigqueue *q) __sigqueue_free(q); } =20 -int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type,= int si_private) +static void posixtimer_queue_sigqueue(struct sigqueue *q, struct task_stru= ct *t, enum pid_type type) { - int sig =3D q->info.si_signo; struct sigpending *pending; + int sig =3D q->info.si_signo; + + signalfd_notify(t, sig); + pending =3D (type !=3D PIDTYPE_PID) ? &t->signal->shared_pending : &t->pe= nding; + list_add_tail(&q->list, &pending->list); + sigaddset(&pending->signal, sig); + complete_signal(sig, t, type); +} + +/* + * This function is used by POSIX timers to deliver a timer signal. + * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID + * set), the signal must be delivered to the specific thread (queues + * into t->pending). + * + * Where type is not PIDTYPE_PID, signals must be delivered to the + * process. In this case, prefer to deliver to current if it is in + * the same thread group as the target process, which avoids + * unnecessarily waking up a potentially idle task. + */ +static inline struct task_struct *posixtimer_get_target(struct k_itimer *t= mr) +{ + struct task_struct *t =3D pid_task(tmr->it_pid, tmr->it_pid_type); + + if (t && tmr->it_pid_type !=3D PIDTYPE_PID && same_thread_group(t, curren= t)) + t =3D current; + return t; +} + +int posixtimer_send_sigqueue(struct k_itimer *tmr) +{ + struct sigqueue *q =3D tmr->sigq; + int sig =3D q->info.si_signo; struct task_struct *t; unsigned long flags; int ret, result; =20 - if (WARN_ON_ONCE(!(q->flags & SIGQUEUE_PREALLOC))) - return 0; - if (WARN_ON_ONCE(q->info.si_code !=3D SI_TIMER)) - return 0; + guard(rcu)(); =20 - ret =3D -1; - rcu_read_lock(); - - /* - * This function is used by POSIX timers to deliver a timer signal. - * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID - * set), the signal must be delivered to the specific thread (queues - * into t->pending). - * - * Where type is not PIDTYPE_PID, signals must be delivered to the - * process. In this case, prefer to deliver to current if it is in - * the same thread group as the target process, which avoids - * unnecessarily waking up a potentially idle task. - */ - t =3D pid_task(pid, type); + t =3D posixtimer_get_target(tmr); if (!t) - goto ret; - if (type !=3D PIDTYPE_PID && same_thread_group(t, current)) - t =3D current; + return -1; + if (!likely(lock_task_sighand(t, &flags))) - goto ret; + return -1; =20 /* * Update @q::info::si_sys_private for posix timer signals with @@ -1988,30 +2002,24 @@ int send_sigqueue(struct sigqueue *q, st * decides based on si_sys_private whether to invoke * posixtimer_rearm() or not. */ - q->info.si_sys_private =3D si_private; + q->info.si_sys_private =3D tmr->it_signal_seq; =20 ret =3D 1; /* the signal is ignored */ - result =3D TRACE_SIGNAL_IGNORED; - if (!prepare_signal(sig, t, false)) + if (!prepare_signal(sig, t, false)) { + result =3D TRACE_SIGNAL_IGNORED; goto out; + } =20 ret =3D 0; if (unlikely(!list_empty(&q->list))) { result =3D TRACE_SIGNAL_ALREADY_PENDING; goto out; } - - signalfd_notify(t, sig); - pending =3D (type !=3D PIDTYPE_PID) ? &t->signal->shared_pending : &t->pe= nding; - list_add_tail(&q->list, &pending->list); - sigaddset(&pending->signal, sig); - complete_signal(sig, t, type); + posixtimer_queue_sigqueue(q, t, tmr->it_pid_type); result =3D TRACE_SIGNAL_DELIVERED; out: - trace_signal_generate(sig, &q->info, t, type !=3D PIDTYPE_PID, result); + trace_signal_generate(sig, &q->info, t, tmr->it_pid_type !=3D PIDTYPE_PID= , result); unlock_task_sighand(t, &flags); -ret: - rcu_read_unlock(); return ret; } #endif /* CONFIG_POSIX_TIMERS */ --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -307,7 +307,7 @@ int posix_timer_queue_signal(struct k_it =20 timr->it_status =3D state; =20 - ret =3D send_sigqueue(timr->sigq, timr->it_pid, timr->it_pid_type, timr->= it_signal_seq); + ret =3D posixtimer_send_sigqueue(timr); /* If we failed to send the signal the timer stops. */ return ret > 0; }