From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1464AC433F5 for ; Fri, 15 Oct 2021 09:45:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E661961245 for ; Fri, 15 Oct 2021 09:45:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237713AbhJOJrK (ORCPT ); Fri, 15 Oct 2021 05:47:10 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:48878 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232218AbhJOJrE (ORCPT ); Fri, 15 Oct 2021 05:47:04 -0400 Date: Fri, 15 Oct 2021 09:44:56 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1634291096; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XGvmaEWC0vrBD3Er+GWJD1AraesOqVPuhnFh5z116Po=; b=sRnaZMW83areevSy9cO6UsfBgMmajQiw3El5ui8cIF63NPot8ZZ0zE3DJAgkU1rgzVtAXi 9xdwqTrBioQtA9kp26obU9Qumv6reUyAsYz+dIABSSZWVXZqhao7lre5n9h+OvJLWYKPlK cIOUVwRY/uGALVlf/11I2ZZnuCQISOtZaZoF/+6W3CcVmKnJ8vsxOBd4hyic0WSVN+biFP ldlgfKUfWi8Q9pUxk2s39N5LXp6Y9eRrfEwZ8SPq5xl95sa5fB3UG+FHtejcIitntfn0DG /L1Z8aaYo0UO2+9q1M0QirQyw2M5UcUG/Hemou2AR0P5noyaUpTHeoMkVZiYPg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1634291096; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XGvmaEWC0vrBD3Er+GWJD1AraesOqVPuhnFh5z116Po=; b=zW7e3WfrL+jt41WB3j0sVuey5fF1V7tvdGqunXNOhuIBNlVq4AMK1DdA5NKRdu1APRJrfd 4kexI3JkniTToQBQ== From: "tip-bot2 for Sebastian Andrzej Siewior" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] irq_work: Allow irq_work_sync() to sleep if irq_work() no IRQ support. Cc: Sebastian Andrzej Siewior , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211006111852.1514359-3-bigeasy@linutronix.de> References: <20211006111852.1514359-3-bigeasy@linutronix.de> MIME-Version: 1.0 Message-ID: <163429109604.25758.7589260727160739202.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 810979682ccc98dbd83f341c18a2e556c30a7164 Gitweb: https://git.kernel.org/tip/810979682ccc98dbd83f341c18a2e556c30a7164 Author: Sebastian Andrzej Siewior AuthorDate: Wed, 06 Oct 2021 13:18:50 +02:00 Committer: Peter Zijlstra CommitterDate: Fri, 15 Oct 2021 11:25:17 +02:00 irq_work: Allow irq_work_sync() to sleep if irq_work() no IRQ support. irq_work() triggers instantly an interrupt if supported by the architecture. Otherwise the work will be processed on the next timer tick. In worst case irq_work_sync() could spin up to a jiffy. irq_work_sync() is usually used in tear down context which is fully preemptible. Based on review irq_work_sync() is invoked from preemptible context and there is one waiter at a time. This qualifies it to use rcuwait for synchronisation. Let irq_work_sync() synchronize with rcuwait if the architecture processes irqwork via the timer tick. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211006111852.1514359-3-bigeasy@linutronix.de --- include/linux/irq_work.h | 3 +++ kernel/irq_work.c | 10 ++++++++++ 2 files changed, 13 insertions(+) diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index ec2a47a..b48955e 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -3,6 +3,7 @@ #define _LINUX_IRQ_WORK_H #include +#include /* * An entry can be in one of four states: @@ -16,11 +17,13 @@ struct irq_work { struct __call_single_node node; void (*func)(struct irq_work *); + struct rcuwait irqwait; }; #define __IRQ_WORK_INIT(_func, _flags) (struct irq_work){ \ .node = { .u_flags = (_flags), }, \ .func = (_func), \ + .irqwait = __RCUWAIT_INITIALIZER(irqwait), \ } #define IRQ_WORK_INIT(_func) __IRQ_WORK_INIT(_func, 0) diff --git a/kernel/irq_work.c b/kernel/irq_work.c index db8c248..e789bed 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -160,6 +160,9 @@ void irq_work_single(void *arg) * else claimed it meanwhile. */ (void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY); + + if (!arch_irq_work_has_interrupt()) + rcuwait_wake_up(&work->irqwait); } static void irq_work_run_list(struct llist_head *list) @@ -204,6 +207,13 @@ void irq_work_tick(void) void irq_work_sync(struct irq_work *work) { lockdep_assert_irqs_enabled(); + might_sleep(); + + if (!arch_irq_work_has_interrupt()) { + rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work), + TASK_UNINTERRUPTIBLE); + return; + } while (irq_work_is_busy(work)) cpu_relax();