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[2620:137:e000::1:20]) by mx.google.com with ESMTP id y20-20020a1709029b9400b0016c223ea41asi13418555plp.209.2022.07.12.13.41.51; Tue, 12 Jul 2022 13:42:29 -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=@kernel-dk.20210112.gappssmtp.com header.s=20210112 header.b=4S57N1Dp; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233456AbiGLUkS (ORCPT + 99 others); Tue, 12 Jul 2022 16:40:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232771AbiGLUkA (ORCPT ); Tue, 12 Jul 2022 16:40:00 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF5E8CD3CB for ; Tue, 12 Jul 2022 13:39:59 -0700 (PDT) Received: by mail-pf1-x436.google.com with SMTP id v7so6400212pfb.0 for ; Tue, 12 Jul 2022 13:39:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=from:to:in-reply-to:references:subject:message-id:date:mime-version :content-transfer-encoding; bh=OLmzDzmTPzMJ38g54k0QU/ejd1TogD/xDNa2/MNxm8Y=; b=4S57N1Dp6yzh3XLZSy5FPy2xCSspLu5nsV+/x1gMHo5unctBf5APbeNGoJ5CcQz5ce E4fgelVwI1LfT1apnNBWVrNjNMZXlrmcMvRyGey8lRtfHq1D5GYFNUsVSgIs3S9DY4Ry pjuZwC3sCNTwShONX2njsmi3sHcscnWgwtThDMIqhoUTaqwzOVuKTXD3lZTfC1jI1X+u rY+YAEiTfSgMsGBp86XkeAhww2EJpo++SXHolzsQ3a10q7B9+mU50SUKKeU5G3TZx/6X R81Brwd4eNlVhJnLsYuv2oO8T0NkyGHwPsup+TM5i/svdTGU8AcnxSbVTXHj1yaAbODG 5OBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:in-reply-to:references:subject :message-id:date:mime-version:content-transfer-encoding; bh=OLmzDzmTPzMJ38g54k0QU/ejd1TogD/xDNa2/MNxm8Y=; b=sj4asZHw7mwI5Zu8Swc1lhkzDwu9v/1un+c47wrOyOZpUvAyLl30w34gi3yWABdn8p MDx37gVT3asYGQjbaUX4kOfgu7ol9X/3nMz9mPvzProKZupAyqSw/AAvVWJHtkkmEe9w hXx5yU3fM5OknKNGnJ2ccx/ILrRNlEoqFGDwgSyfZ2vdKvh/OMCXB9pz4UjdkKlXBb7U bPU3Qt7seD+ooiC59VNz8cNaMZ/Eh3jMj6UhDhuRh4LDNkU7OUeZAEKdmjbt+Mcawku4 YI5qPD+2L++51rzO/ewFTorsOHKpxH6x5etiLLIg7YZIBA8ZEKFtBIuofWAAURepgzAm aNZA== X-Gm-Message-State: AJIora+FdriEfP93I2jOjXPCuAArV/jZKDPY3CDz9ZTqFWAxGmGZZYwW J9WdiaTERgbeFft+BmYyMDObDw6YhUnH6A== X-Received: by 2002:a63:540d:0:b0:412:9fb2:4d4 with SMTP id i13-20020a63540d000000b004129fb204d4mr41273pgb.475.1657658399182; Tue, 12 Jul 2022 13:39:59 -0700 (PDT) Received: from [127.0.1.1] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id p8-20020a17090a930800b001e292e30129sm19266pjo.22.2022.07.12.13.39.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jul 2022 13:39:58 -0700 (PDT) From: Jens Axboe To: ubizjak@gmail.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org In-Reply-To: <20220712150547.5786-1-ubizjak@gmail.com> References: <20220712150547.5786-1-ubizjak@gmail.com> Subject: Re: [PATCH v2] block/rq_qos: Use atomic_try_cmpxchg in atomic_inc_below Message-Id: <165765839842.44219.4233753152017615209.b4-ty@kernel.dk> Date: Tue, 12 Jul 2022 14:39:58 -0600 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=unavailable 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 On Tue, 12 Jul 2022 17:05:47 +0200, Uros Bizjak wrote: > Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in > atomic_inc_below. 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, atomic_try_cmpxchg implicitly assigns old *ptr value to "old" when > cmpxchg fails, enabling further code simplifications. > > [...] Applied, thanks! [1/1] block/rq_qos: Use atomic_try_cmpxchg in atomic_inc_below commit: f4b1e27db49c8b985b116aa99481b4c6a4342ed4 Best regards, -- Jens Axboe