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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 540B2C433F5 for ; Tue, 18 Jan 2022 11:18:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239954AbiARLS0 (ORCPT ); Tue, 18 Jan 2022 06:18:26 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:35068 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239854AbiARLSL (ORCPT ); Tue, 18 Jan 2022 06:18:11 -0500 Date: Tue, 18 Jan 2022 11:18:09 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1642504690; 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=Bk/9twIBlVgr/UmrtZdDPQtXp5zaM6nzEXilX/lUysA=; b=JNPmiNtq5IEzGnwkBusuzeZuFCf7obaBiqwGaDOAzIm59BMSsz4xCTdJ1ATV0QCV2JS/gR 4KeFEeqMShjr3+QpawHUXSt4258iCw/8qIdZXoneU7wBBzg5lwvIUVDZXUW99qr5eXh4XE G3Ln1+tH+mQW3e/cJ6GYPvP2GtmnF8EYsXt7hWpkRwzFJfVAPSjyoL5XAz+PhuoHGWk5oP ccRi4/txs6zsXnmMLUZf2jn3/GSjIUUObEkp9t9CklgM5uX7wTp6hniIt3tUpwqY0ezbn5 08/knmLR8ISP6wfzDNg0XJKa9rb288HB+KYkWom2cUsGYaTmyyRylRFaaNKjbA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1642504690; 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=Bk/9twIBlVgr/UmrtZdDPQtXp5zaM6nzEXilX/lUysA=; b=31hGylwayp3rduEJfmdQZg1Hs5o9gkqq/H7zb4ZaCaciloulld2l1eiSRW+FbgNCiHFkJ9 P3+HGST00lE/NIDw== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched: Avoid double preemption in __cond_resched_*lock*() Cc: xuhaifeng , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: MIME-Version: 1.0 Message-ID: <164250468946.16921.3796443718413078010.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/urgent branch of tip: Commit-ID: 7e406d1ff39b8ee574036418a5043c86723170cf Gitweb: https://git.kernel.org/tip/7e406d1ff39b8ee574036418a5043c86723170cf Author: Peter Zijlstra AuthorDate: Sat, 25 Dec 2021 01:04:57 +01:00 Committer: Peter Zijlstra CommitterDate: Tue, 18 Jan 2022 12:09:59 +01:00 sched: Avoid double preemption in __cond_resched_*lock*() For PREEMPT/DYNAMIC_PREEMPT the *_unlock() will already trigger a preemption, no point in then calling preempt_schedule_common() *again*. Use _cond_resched() instead, since this is a NOP for the preemptible configs while it provide a preemption point for the others. Reported-by: xuhaifeng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YcGnvDEYBwOiV0cR@hirez.programming.kicks-ass.net --- kernel/sched/core.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0d2ab2a..56b428c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8218,9 +8218,7 @@ int __cond_resched_lock(spinlock_t *lock) if (spin_needbreak(lock) || resched) { spin_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; spin_lock(lock); @@ -8238,9 +8236,7 @@ int __cond_resched_rwlock_read(rwlock_t *lock) if (rwlock_needbreak(lock) || resched) { read_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; read_lock(lock); @@ -8258,9 +8254,7 @@ int __cond_resched_rwlock_write(rwlock_t *lock) if (rwlock_needbreak(lock) || resched) { write_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; write_lock(lock);