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 A98FDC433F5 for ; Mon, 14 Feb 2022 10:02:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233557AbiBNKCy (ORCPT ); Mon, 14 Feb 2022 05:02:54 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:43494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344276AbiBNJ6a (ORCPT ); Mon, 14 Feb 2022 04:58:30 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37BCA65836; Mon, 14 Feb 2022 01:46:09 -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 B57C461200; Mon, 14 Feb 2022 09:46:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B9A7C340E9; Mon, 14 Feb 2022 09:46:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644831968; bh=Gp4lZMUWtUqof2YOT21LQIdrUUR7ioeSZppaIqJ5ESE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MKOjcjdKHEhu4jmGotdY6sRKUjcHAsqylNie6xwz1CdI2Bl3RTrw6Yki0uy0tOK7Y qTfLi4xxhdpPsaYfLM6w6Wlb7RSjM3zBrLxsMD4W1p6HyM9K9iakncwANLjv2chR/t BEU19wsQ8g45KlZkxK62UaFjGsWIC+K8NrvJstUI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, xuhaifeng , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.15 038/172] sched: Avoid double preemption in __cond_resched_*lock*() Date: Mon, 14 Feb 2022 10:24:56 +0100 Message-Id: <20220214092507.716840592@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092506.354292783@linuxfoundation.org> References: <20220214092506.354292783@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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