From nobody Wed Feb 11 11:28:08 2026 Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com [209.85.167.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C52A43A1BF for ; Thu, 23 May 2024 07:35:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716449755; cv=none; b=fjRh1XFyO2mLcyaSH5xIA0yHOflgeH5+nbJaVSdoQ1lMphu5hdS4GWdkJBM0I3wX2jh3cLla1WyNzz52o4qUUfx2e3emKCo343DiAfHzuFLun6QBvmV7NU+VoUz6DB0Klmjww5yd41255XkCbTieiv0VJ02MigTX8dtOrDQyKvo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716449755; c=relaxed/simple; bh=ncs1lAlk+fu9rWEPB1hvPGNLy664a14YaFIYHbF/HfU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ePsWraDbbPkRwSmLerEo2Lv10bv7paWym8gutExKDR6n+lSJnE1fA8vFS5Y7XdJEE+0wBAyk7Uw9CC8/MVP61mKjlBz94diqads6eW0qpsH8khGB5wFAVQktq9dmvjWXSMWN04GUEh1IrDA7PBW6fI6a8FlLW7WbbswmyLC+L8Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OCTZxrXb; arc=none smtp.client-ip=209.85.167.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OCTZxrXb" Received: by mail-lf1-f43.google.com with SMTP id 2adb3069b0e04-5231efd80f2so8117334e87.2 for ; Thu, 23 May 2024 00:35:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1716449751; x=1717054551; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=3+NKs2DIKniT5pwrnywyYUogTT0Vo2nz647Z/Tvq1cg=; b=OCTZxrXbpCJ8XQVg9hrv4EgJLP3PQpx0zP+3ko86ZJ5nXgYGtKOtby8T/V2yJcWZoU KFlTOlsRoeUQ7rnkTCfz2Qe+0WsCi2AxvPTjRGRWM16eQnv49+hqQa+oaxTT8vDh3kCs zvCTqV7JVpEmcdVvH265sbpplZm4xNWMGRKaW+01yakMEBuuyTdmLftA9EOC525nHPUz yQRVFIQDH0VHlkehmNCiwnkujaZr/YZzCRWy/FRCyOcNJJhx6hKcxy5SBoUy7sKIlfWW 36137jvvLkCZYDFlOlxN41xjgUYSjFkXTuIXYeGmuC7Ori6uFCLbeHOy4fZLnBHdRrBi PLGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716449751; x=1717054551; 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=3+NKs2DIKniT5pwrnywyYUogTT0Vo2nz647Z/Tvq1cg=; b=oAaincZh594oDTiw8078WfQmPOpT+JdKN5BLxWfKC9J9YWtFtWOrUPsq7rvlXLRKTU QeweDUetSxmbgirB1HXTQ5Q+Fce04kclSPhhPssMGJGMAl7PqXPazaqKAUbLROOLpejY Oq1io7/wEGYoMGTYTX0Ig46PyGHHSm+UxDwWuklbjh/6wxgd50mMnckfmsMv5RV7melx gVwo5spZACja/7tOSZLLAnZN3pcQsfG3rJxffBgmEBjfS1EMqLZOOqMNxqcYaYG1XKjR 3q0z7WsaefEHpZrU/b7QjADXiNHYCvKdHGE9g59FmURt3T7kKvwO8MbuPVN4sKnBP8sz xN8g== X-Gm-Message-State: AOJu0YzDSnnNxMXnDHFKIbz+d8OCULd10JpvEjdpSI902Z/jlrB4Rp/8 iLTDGUm1D3sYfyGAfNkobiAvx9ManJpUmdsRfEq//Oja8Bs2ne9Qjg4SI6EP X-Google-Smtp-Source: AGHT+IFjE7brsmCeTCMtAdy9S8PLMAN9C2HfTZuQd930iGIV1jihMa/zhajVY+dsQcfBJXKj5bsvsA== X-Received: by 2002:ac2:54a9:0:b0:521:44ce:2999 with SMTP id 2adb3069b0e04-526c0c544fcmr2594388e87.47.1716449750762; Thu, 23 May 2024 00:35:50 -0700 (PDT) Received: from fedora.iskraemeco.si ([193.77.86.250]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3502b79bc99sm35840452f8f.11.2024.05.23.00.35.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 May 2024 00:35:50 -0700 (PDT) From: Uros Bizjak To: linux-kernel@vger.kernel.org Cc: Uros Bizjak , Andrew Morton Subject: [PATCH] fork: Use this_cpu_try_cmpxchg() in try_release_thread_stack_to_cache() Date: Thu, 23 May 2024 09:35:14 +0200 Message-ID: <20240523073530.8128-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.45.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use this_cpu_try_cmpxchg() instead of this_cpu_cmpxchg (*ptr, old, new) =3D=3D old in try_release_thread_stack_to_cache. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). No functional change intended. Signed-off-by: Uros Bizjak Cc: Andrew Morton --- kernel/fork.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/fork.c b/kernel/fork.c index 99076dbe27d8..c9e994d66930 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -205,7 +205,9 @@ static bool try_release_thread_stack_to_cache(struct vm= _struct *vm) unsigned int i; =20 for (i =3D 0; i < NR_CACHED_STACKS; i++) { - if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) !=3D NULL) + struct vm_struct *tmp =3D NULL; + + if (!this_cpu_try_cmpxchg(cached_stacks[i], &tmp, vm)) continue; return true; } --=20 2.45.1