From patchwork Tue Sep 1 15:10:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 264757 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F4A6C433E6 for ; Tue, 1 Sep 2020 15:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50E6620E65 for ; Tue, 1 Sep 2020 15:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974409; bh=TJXeZSGzwfNiVC7VyxV4h8RVxP7uqTTnzNYyvYWstFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1I8sxt92bJvLgsJl6VR8Ug5Ud87HCItpByBaoBhLk7ZVZcOSj7gagdaCtdlMWvkve qTy6knoyNQABqNQ/eDNqMlcEFFzWMuUdZKtRssKqmcnueMLXS+TOR3OA9Fgzic78Ms NUwByFje5iKIcD7H+iK+gcGovOR64kLRQ9ToLWeY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728142AbgIAPd2 (ORCPT ); Tue, 1 Sep 2020 11:33:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:37622 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731167AbgIAPd0 (ORCPT ); Tue, 1 Sep 2020 11:33:26 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5A994205F4; Tue, 1 Sep 2020 15:33:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974405; bh=TJXeZSGzwfNiVC7VyxV4h8RVxP7uqTTnzNYyvYWstFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hu0djrURqG6Eo3CobaGPRrdqkL57+nJyG+YLg6IOqkGl7FKqlanUpASgQDW8B0Wbq NuGj+1guTp93HQxjOpXoUGMlgf4f/nMG4NbhjU/GtRiwIs326VHBMX7Fp72yT6AChS 5hNtbiSNLgnQUhQGg1ddovdGKrnXo5b/4Cj31QGQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Oberparleiter , Vineeth Vijayan , Heiko Carstens , Sasha Levin Subject: [PATCH 5.4 133/214] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Tue, 1 Sep 2020 17:10:13 +0200 Message-Id: <20200901150959.357707885@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150952.963606936@linuxfoundation.org> References: <20200901150952.963606936@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vineeth Vijayan [ Upstream commit 0b8eb2ee9da1e8c9b8082f404f3948aa82a057b2 ] The scanning through subchannels during the time of an event could take significant amount of time in case of platforms with lots of known subchannels. This might result in higher scheduling latencies for other tasks especially on systems with a single CPU. Add cond_resched() call, as the loop in slow_eval_known_fn() can be executed for a longer duration. Reviewed-by: Peter Oberparleiter Signed-off-by: Vineeth Vijayan Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- drivers/s390/cio/css.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 831850435c23b..5734a78dbb8e6 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -677,6 +677,11 @@ static int slow_eval_known_fn(struct subchannel *sch, void *data) rc = css_evaluate_known_subchannel(sch, 1); if (rc == -EAGAIN) css_schedule_eval(sch->schid); + /* + * The loop might take long time for platforms with lots of + * known devices. Allow scheduling here. + */ + cond_resched(); } return 0; }