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 69386C433F5 for ; Mon, 14 Feb 2022 10:23:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346967AbiBNKXL (ORCPT ); Mon, 14 Feb 2022 05:23:11 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:51396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347149AbiBNKUu (ORCPT ); Mon, 14 Feb 2022 05:20:50 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA1CB6E359; Mon, 14 Feb 2022 01:55:32 -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 ams.source.kernel.org (Postfix) with ESMTPS id 3C39BB80D83; Mon, 14 Feb 2022 09:55:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 470F7C36AF6; Mon, 14 Feb 2022 09:55:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644832508; bh=MwkTiZJoksLSxaggOf2WpxBsuCuWyZjip0DdOvCxCRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PFoy/y/QFmgTKXsHi+x7Qepr3wFfFNAyI+PhUhMm7BwSrfAAYPTmiLOH+zSCVQhh5 Ex9Gy0vnfrR7MnrBmGahJr5L2vyFDIInFgF3R7h6BkiY6Ug+TbhujdVj97Ek9lFdjJ rb+E87+M6QlaLBgVOcqd3+JWdTqIi3V/rGE5XGVU= 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 5.16 035/203] sched: Avoid double preemption in __cond_resched_*lock*() Date: Mon, 14 Feb 2022 10:24:39 +0100 Message-Id: <20220214092511.400682464@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092510.221474733@linuxfoundation.org> References: <20220214092510.221474733@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 77563109c0ea0..d24823b3c3f9f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8176,9 +8176,7 @@ 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); @@ -8196,9 +8194,7 @@ 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); @@ -8216,9 +8212,7 @@ 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