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 6FAF3C4332F for ; Thu, 3 Feb 2022 20:36:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355411AbiBCUfv (ORCPT ); Thu, 3 Feb 2022 15:35:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354476AbiBCUdo (ORCPT ); Thu, 3 Feb 2022 15:33:44 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 632ECC0617BC; Thu, 3 Feb 2022 12:33:16 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0150D61B05; Thu, 3 Feb 2022 20:33:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80802C340F0; Thu, 3 Feb 2022 20:33:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643920395; bh=Gp4lZMUWtUqof2YOT21LQIdrUUR7ioeSZppaIqJ5ESE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EMdY4PkJxRwh1HG8d9SdN7Ecsl84r5tkDUYY7LNrqEd+ImWXaITmCSg4falhGWf/L 7LxkQ76G4PJ5h1WbXFTSKnDAe9jqd5zjYLgGrsUtMX/ZybhYJxBm2eWZA40Yto4gUR s3h4ho4OpX4kXnQGHZKOGAp+fv5J3VPz2uxWxr1PfmJWwhC1bLb6kyIVVYjxQC5ubc PMZ2xXXUtEQTep7Oh7qrS162HGQ8Du7r7UI9X2Yjkc+XgKXUvJKXvWIWZd3haBOpY0 lGEdZES6xZGrKyf4My94w53pSP+8gz4pkzkEhCB04Bl0Bx+X3EWKI8IyMl/t2kvAY5 mpdD1q6WE9F7A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Zijlstra , xuhaifeng , Sasha Levin , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org Subject: [PATCH AUTOSEL 5.15 18/41] sched: Avoid double preemption in __cond_resched_*lock*() Date: Thu, 3 Feb 2022 15:32:22 -0500 Message-Id: <20220203203245.3007-18-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220203203245.3007-1-sashal@kernel.org> References: <20220203203245.3007-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra [ Upstream commit 7e406d1ff39b8ee574036418a5043c86723170cf ] 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 Signed-off-by: Sasha Levin --- 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 0d12ec7be3017..c2dec6ce98091 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8199,9 +8199,7 @@ 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); @@ -8219,9 +8217,7 @@ 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); @@ -8239,9 +8235,7 @@ 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); -- 2.34.1