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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 E0D4CC433ED for ; Thu, 15 Apr 2021 14:24:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8230613BA for ; Thu, 15 Apr 2021 14:24:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233247AbhDOOYw (ORCPT ); Thu, 15 Apr 2021 10:24:52 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:16594 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230056AbhDOOYv (ORCPT ); Thu, 15 Apr 2021 10:24:51 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4FLhPD0R9jz19Lkm; Thu, 15 Apr 2021 22:22:08 +0800 (CST) Received: from thunder-town.china.huawei.com (10.174.179.202) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.498.0; Thu, 15 Apr 2021 22:24:16 +0800 From: Zhen Lei To: Clemens Ladisch , Arnd Bergmann , "Greg Kroah-Hartman" , linux-kernel CC: Zhen Lei , Nils Carlson , Andrew Morton Subject: [PATCH 1/1] char: hpet: Remove unused local variable 'm' in hpet_interrupt() Date: Thu, 15 Apr 2021 22:24:04 +0800 Message-ID: <20210415142404.3846-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.174.179.202] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 273ef9509b79 ("drivers/char/hpet.c: fix periodic-emulation for delayed interrupt") removed the reference to local variable 'm', but forgot to remove the definition and assignment of it. Due to read_counter() indirectly calls "read barrier", the performance is slightly degraded. Since the following comments give some description based on 'm', so move the assignment of 'm' into it. Fixes: 273ef9509b79 ("drivers/char/hpet.c: fix periodic-emulation for delayed interrupt") Reported-by: Hulk Robot Signed-off-by: Zhen Lei --- drivers/char/hpet.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c index ed3b7dab678dbd1..46950a0cda181a1 100644 --- a/drivers/char/hpet.c +++ b/drivers/char/hpet.c @@ -156,14 +156,16 @@ static irqreturn_t hpet_interrupt(int irq, void *data) * This has the effect of treating non-periodic like periodic. */ if ((devp->hd_flags & (HPET_IE | HPET_PERIODIC)) == HPET_IE) { - unsigned long m, t, mc, base, k; + unsigned long t, mc, base, k; struct hpet __iomem *hpet = devp->hd_hpet; struct hpets *hpetp = devp->hd_hpets; t = devp->hd_ireqfreq; - m = read_counter(&devp->hd_timer->hpet_compare); mc = read_counter(&hpet->hpet_mc); - /* The time for the next interrupt would logically be t + m, + /* + * m = read_counter(&devp->hd_timer->hpet_compare); + * + * The time for the next interrupt would logically be t + m, * however, if we are very unlucky and the interrupt is delayed * for longer than t then we will completely miss the next * interrupt if we set t + m and an application will hang. -- 2.26.0.106.g9fadedd