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[2620:137:e000::1:20]) by mx.google.com with ESMTP id w20-20020a05620a129400b0074fc1cfb2c9si6022314qki.685.2023.06.06.08.43.11; Tue, 06 Jun 2023 08:43:25 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=cZacQ8wY; dkim=neutral (no key) header.i=@linutronix.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238324AbjFFOk7 (ORCPT + 99 others); Tue, 6 Jun 2023 10:40:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238049AbjFFOj3 (ORCPT ); Tue, 6 Jun 2023 10:39:29 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63DF2173B for ; Tue, 6 Jun 2023 07:38:31 -0700 (PDT) Message-ID: <20230606142033.384181292@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1686062306; 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=LYF80Bk8/VFt3/Zfq3hqFvDVFoPNEcj4ORUMtha4AAY=; b=cZacQ8wYAB7Fb9DsCdI9e5upBjaTR3/GonogUx1w32o7gnoJL8+oGIBsGZRjWoLL+9KRvV ZF8AjijMZ6myMI0e5MjuVzggO9U6nzZvgkZ4NM5NmQBDDbozZgEm/bzfeQ9yFWJR7n2kp9 DoYdIPD8R/+9CdHtmfpldGwPzv8AdJudlXDytEpOKs1/HM/QvBGZusnYeGZvZGZ92pYiag IyM7pJ/3zaWS/wNloxDpFu1X3UENzr9+5RgPiZ9iJcC7TN4UgfeNEr+j5xFWK8U9QJbpCF X0TEOM1VbVURlL97TkNbqOjr32eMih58SBLQy7kpnwzA4iNKDLcf01PslOTFwg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1686062306; 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=LYF80Bk8/VFt3/Zfq3hqFvDVFoPNEcj4ORUMtha4AAY=; b=BqlduYM4tBY34xpYtNtBJa2wlNU+kRrBw7+Hr5IfTnIWZ4dF+Q1zbvXE49vkvTgr9KSJwU m4OySW2lELrVxJCQ== From: Thomas Gleixner To: LKML Cc: Frederic Weisbecker , Anna-Maria Behnsen , John Stultz , Peter Zijlstra , Ingo Molnar , Stephen Boyd , Eric Biederman , Oleg Nesterov Subject: [patch 42/45] signal: Queue ignored posixtimers on ignore list References: <20230606132949.068951363@linutronix.de> MIME-Version: 1.0 Date: Tue, 6 Jun 2023 16:38:25 +0200 (CEST) X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1767968557838924104?= X-GMAIL-MSGID: =?utf-8?q?1767968557838924104?= Queue posixtimers which have their signal ignored on the ignored list: 1) When the timer fires and the signal has SIG_IGN set 2) When SIG_IGN is installed via sigaction() and a timer signal is queued This completes the SIG_IGN handling and such timers are not longer self rearmed which avoids pointless wakeups. Signed-off-by: Thomas Gleixner --- kernel/signal.c | 44 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 8 deletions(-) --- a/kernel/signal.c +++ b/kernel/signal.c @@ -725,6 +725,16 @@ void signal_wake_up_state(struct task_st kick_process(t); } +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q); + +static void sigqueue_free_ignored(struct task_struct *ptmr_tsk, struct sigqueue *q) +{ + if (likely(!ptmr_tsk || q->info.si_code != SI_TIMER)) + __sigqueue_free(q); + else + posixtimer_sig_ignore(ptmr_tsk, q); +} + /* * Remove signals in mask from the pending set and queue. * @@ -743,7 +753,7 @@ static void flush_sigqueue_mask(sigset_t list_for_each_entry_safe(q, n, &s->list, list) { if (sigismember(mask, q->info.si_signo)) { list_del_init(&q->list); - __sigqueue_free(q); + sigqueue_free_ignored(ptmr_tsk, q); } } } @@ -1956,9 +1966,8 @@ int posixtimer_send_sigqueue(struct k_it int sig = q->info.si_signo; struct task_struct *t; unsigned long flags; - int ret, result; + int result; - ret = -1; rcu_read_lock(); t = posixtimer_get_target(tmr); @@ -2004,13 +2013,24 @@ int posixtimer_send_sigqueue(struct k_it */ q->info.si_overrun = 0; - ret = 1; /* the signal is ignored */ if (!prepare_signal(sig, t, false)) { result = TRACE_SIGNAL_IGNORED; + + /* Paranoia check. Try to survive. */ + if (WARN_ON_ONCE(!list_empty(&q->list))) + goto out; + + if (hlist_unhashed(&tmr->ignored_list)) { + hlist_add_head(&tmr->ignored_list, &t->signal->ignored_posix_timers); + posixtimer_sigqueue_getref(q); + } goto out; } - ret = 0; + /* This should never happen and leaks a reference count */ + if (WARN_ON_ONCE(!hlist_unhashed(&tmr->ignored_list))) + hlist_del_init(&tmr->ignored_list); + if (unlikely(!list_empty(&q->list))) { /* This holds a reference count already */ result = TRACE_SIGNAL_ALREADY_PENDING; @@ -2025,7 +2045,14 @@ int posixtimer_send_sigqueue(struct k_it unlock_task_sighand(t, &flags); ret: rcu_read_unlock(); - return ret; + return 0; +} + +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) +{ + struct k_itimer *tmr = container_of(q, struct k_itimer, sigq); + + hlist_add_head(&tmr->ignored_list, &tsk->signal->ignored_posix_timers); } static void posixtimer_sig_unignore(struct task_struct *tsk, int sig) @@ -2074,6 +2101,7 @@ static void posixtimer_sig_unignore(stru } } #else /* CONFIG_POSIX_TIMERS */ +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) { } static inline void posixtimer_sig_unignore(struct task_struct *tsk, int sig) { } #endif /* !CONFIG_POSIX_TIMERS */ @@ -4214,9 +4242,9 @@ int do_sigaction(int sig, struct k_sigac if (sig_handler_ignored(sig_handler(p, sig), sig)) { sigemptyset(&mask); sigaddset(&mask, sig); - flush_sigqueue_mask(&mask, &p->signal->shared_pending, NULL); + flush_sigqueue_mask(&mask, &p->signal->shared_pending, p); for_each_thread(p, t) - flush_sigqueue_mask(&mask, &t->pending, NULL); + flush_sigqueue_mask(&mask, &t->pending, p); } else if (was_ignored) { posixtimer_sig_unignore(p, sig); }