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[2620:137:e000::1:20]) by mx.google.com with ESMTP id f33-20020a17090a702400b00262dc983a99si16842445pjk.91.2023.07.03.08.22.25; Mon, 03 Jul 2023 08:22:53 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=Hq70A1i7; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231307AbjGCOx6 (ORCPT + 99 others); Mon, 3 Jul 2023 10:53:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbjGCOx6 (ORCPT ); Mon, 3 Jul 2023 10:53:58 -0400 Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 235AC10E; Mon, 3 Jul 2023 07:53:57 -0700 (PDT) Received: by mail-ej1-x633.google.com with SMTP id a640c23a62f3a-98dfb3f9af6so562110266b.2; Mon, 03 Jul 2023 07:53:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1688396035; x=1690988035; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=nj6RWQmoOrElPG2s/9G/TB0K+w3PkNfdcrWXDb193cE=; b=Hq70A1i7yhzs1W5neAZ6mYcg4FV5acbes7/oOHmYlzA1qmpOutqn5uB/eFdD6cl6x7 GCpwqxWA+VX20QE+lWprYhmi5ofH0ZOpEHdlUj4xlxpLejdErLB1CClgpAkD6v0Q76qo CNHAZw4QEDc/KHV5esfckBQG06VUZU0WhFNmKx7175ePnuE16aBOUR7N4L/3JL3EmM2s QhK8NSMnRr6Wjznv1bEkUoBuCf49BgaSEALsdSlUH+byg4ZLIrYesrrz1YPH+jV468Sp +Umohq6Yr/ph7m9QjIO/ggMlgojRyoIOgjxfXF7RH5/YUp0KLR2B64Hev3QzIzcmocMC kfbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688396035; x=1690988035; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=nj6RWQmoOrElPG2s/9G/TB0K+w3PkNfdcrWXDb193cE=; b=CEmDkZEgcoX6khqd2wQTfM8En5ZIAxeEC59GEVCfcnCV/QvIGKWZiKO9QZSlHFkHKJ 4RjrgM64aJtUzJjDaZ8E2YsAGLDhkTDME5SQrf0R1hSVZj+mo8u23Cs+5L28/TBDxPoM 1kkQEWA/d18fIe9il88iV6UFOvSlAsHtgcKnf8mxpg8nw4RVbueXyMDQLt1oT3ZBZCtn jQC/tjG2uxAcRCbsKrpNMC0SaPyFQ+BV9lglfbJ120y3WgEFvTprgDIj2IELy8YKBpZX mb0Oln3lGqFVpm0Bv/hhzPbgBeN7K3sWwm8HQfV4JaB8oseNJiNKJ0uzIXFqcg/L1qLy ieSA== X-Gm-Message-State: ABy/qLZEyBHqqk5zAQqObWSgZClyn0E1w0ofzpp/9sqqRaxi/zjPgrPQ vPQsgtjTePK+nda1/HX4Quqbc2G0PJtrNA== X-Received: by 2002:a17:906:5904:b0:98e:973:d39f with SMTP id h4-20020a170906590400b0098e0973d39fmr8177403ejq.33.1688396035170; Mon, 03 Jul 2023 07:53:55 -0700 (PDT) Received: from localhost.localdomain ([46.248.82.114]) by smtp.gmail.com with ESMTPSA id e18-20020a17090681d200b00992ed412c74sm4545661ejx.88.2023.07.03.07.53.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jul 2023 07:53:54 -0700 (PDT) From: Uros Bizjak To: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Uros Bizjak , Fenghua Yu , Dave Jiang , Vinod Koul Subject: [PATCH] dmaengine:idxd: Use local64_try_cmpxchg in perfmon_pmu_event_update Date: Mon, 3 Jul 2023 16:52:37 +0200 Message-ID: <20230703145346.5206-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use local64_try_cmpxchg instead of local64_cmpxchg (*ptr, old, new) == old in perfmon_pmu_event_update. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails. There is no need to re-read the value in the loop. No functional change intended. Cc: Fenghua Yu Cc: Dave Jiang Cc: Vinod Koul Signed-off-by: Uros Bizjak --- drivers/dma/idxd/perfmon.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/dma/idxd/perfmon.c b/drivers/dma/idxd/perfmon.c index d73004f47cf4..fdda6d604262 100644 --- a/drivers/dma/idxd/perfmon.c +++ b/drivers/dma/idxd/perfmon.c @@ -245,12 +245,11 @@ static void perfmon_pmu_event_update(struct perf_event *event) int shift = 64 - idxd->idxd_pmu->counter_width; struct hw_perf_event *hwc = &event->hw; + prev_raw_count = local64_read(&hwc->prev_count); do { - prev_raw_count = local64_read(&hwc->prev_count); new_raw_count = perfmon_pmu_read_counter(event); - } while (local64_cmpxchg(&hwc->prev_count, prev_raw_count, - new_raw_count) != prev_raw_count); - + } while (!local64_try_cmpxchg(&hwc->prev_count, + &prev_raw_count, new_raw_count)); n = (new_raw_count << shift); p = (prev_raw_count << shift); -- 2.41.0