From nobody Fri Dec 19 14:22:25 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E6B62BEC42; Wed, 5 Nov 2025 22:03:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762380189; cv=none; b=H5oplYHRWbC4qdvCbrVHz3MfbTsqx7+ophO2G8HLgLE/1SPXrnD4C+7xDsjmOdt83q45CzDLwXFAS7/UBlNyIcHA3HXsqs35IZ0yFbrKPGyds64cB2mBLIkOd8UyRBPRO7OG9w3ZrGMRha840RF8yAukyfQqCXPXvoldTv6Fk9o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762380189; c=relaxed/simple; bh=AnWwGKeQooPlYbUr+C0sojh6f1NXESUu5BAJbuwV6bE=; h=Date:Message-ID:From:To:Cc:Subject; b=roqZhU6fE2DwLYXatsu229KzVItT0DyxCXl9JyF9iaGIfpE3Qd8M78AkfREd19552ZbQlPwM/eoO7Y+Ikc7IK4lvZywIbHdWDNTTv/RdRkebhrolQKXhmuG2CKjlchQrVYhPKJE9osVSiAKLF/7W82n4BEKICN6ELtHy05hEiDw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LiLtOvai; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LiLtOvai" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 060BFC4CEF5; Wed, 5 Nov 2025 22:03:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762380189; bh=AnWwGKeQooPlYbUr+C0sojh6f1NXESUu5BAJbuwV6bE=; h=Date:From:To:Cc:Subject:From; b=LiLtOvaiNRgD/8yTO9mnsIKRu1IllaXug4hoXmqUj3TND8dJRxNmLyV8bKF3cAtk0 wFmlWrJ9Rc4Z+vkfmCspDDeJwtnd892dAd2Bzcf/MLWnRTxLYNtzNJ+hneDuG1hsJj sKjTuuKKnNFYrNlXOrhYKR2MwzgWte8+x7HPqcwzTklwebIXo5S4lRsrFJu2qZCwFG VNDpYmSTz01TSMiBeuZwmESabNWQisFhBwkoSqpz89aFaGCufQ1PTRNBbfBZgP8ACm RREODHCbCWtnydMiB8rhTTI0JAtr3pbyI+ttsMb2pHZo5RHePWQc5MKd6k5Lp68CGS kn7F4K/1TLYew== Date: Wed, 05 Nov 2025 12:03:08 -1000 Message-ID: <5d2305143c29ed781438acc9b92fb781@kernel.org> From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH sched_ext/for-6.19] sched_ext: Mark racy bitfields to prevent adding fields that can't tolerate races Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The warned bitfields in struct scx_sched are updated racily from concurrent CPUs causing RMW races, which is fine for these boolean warning flags. Add a comment marking this area to prevent future fields that can't tolerate racy updates from being added here. Signed-off-by: Tejun Heo --- kernel/sched/ext_internal.h | 4 ++++ 1 file changed, 4 insertions(+) --- a/kernel/sched/ext_internal.h +++ b/kernel/sched/ext_internal.h @@ -895,6 +895,10 @@ struct scx_sched { struct scx_dispatch_q **global_dsqs; struct scx_sched_pcpu __percpu *pcpu; + /* + * Updates to the following warned bitfields can race causing RMW issues + * but it doesn't really matter. + */ bool warned_zero_slice:1; bool warned_deprecated_rq:1;