From mboxrd@z Thu Jan 1 00:00:00 1970 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 CC4EA25D914 for ; Thu, 6 Mar 2025 18:18:24 +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=1741285104; cv=none; b=nmaldXdpmBWAxTJbiYy7QVh/jFJvH7mW3f+dws17KeZ3gLdAfgUhVGST7Yg7W9Ljy/cz/FNCh5Ad8qK9sa8UTnmeWKB+3qE5y6jXfWpLYB0Po8j2Zk+PUGd1efNqwFHdURYjJw0iueqKpdkZJXR/8ekv7wMkvtYvd4xq+G2gSdk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741285104; c=relaxed/simple; bh=NI2nMMuG5HF1v6r5TEd6Xe1TzAZ11OMN6z0zMPV936U=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aHzkmXMj73HC9nxbbGqfPsxnErmyMbOHOtUook1l4AnsS5ay3ESlQfmdFt6+/OMe36kdLmYJb9JwKjKt/W/iEFrbLBZvMZM0V++qo145LzJHGooOyqUzPy0MUymsIgMDm2ABaGLBJgHaW++Xbufl2zatFCz7hiJa/gxI7NvqBX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ejn89qlN; 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="ejn89qlN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E76DC4CEEB; Thu, 6 Mar 2025 18:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741285104; bh=NI2nMMuG5HF1v6r5TEd6Xe1TzAZ11OMN6z0zMPV936U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ejn89qlNMXjoP2ViUiLfSaOn78jE+HVyhOyzvUqpHY3QBRTmueIpbyx95SOzckKsk ffydeNGT4PjB+Wyr1U7i2+ZkoopC5fdHeiCy78b0+mpaSpyKuxORhW7uzSZ2tpnbYC gSt6sz+l4urI8NIvpSw3NLZmGpDcNUx8OhqSNB/3kaGaP4ZaM1+HcEwbdYiDrEw6o2 H4J4P4BYGx1JNKk4Txxakk9GPuMkUBJ5wOOzSzKy5BbnlCySdUxXhBwi2HLB6dhoCy +Fv+xfLYC3FzuiZ4O/WB6QqUB9etPi0lVU4euO2msA13MdBzdzLVA4M7AS0xD84JL1 41NWhok2A3ngw== Date: Thu, 6 Mar 2025 10:18:23 -0800 From: Jakub Kicinski To: Allison Henderson Cc: "netdev@vger.kernel.org" Subject: Re: [PATCH 1/6] net/rds: Avoid queuing superfluous send and recv work Message-ID: <20250306101823.416efa9d@kernel.org> In-Reply-To: References: <20250227042638.82553-1-allison.henderson@oracle.com> <20250227042638.82553-2-allison.henderson@oracle.com> <20250228161908.3d7c997c@kernel.org> <20250304164412.24f4f23a@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 6 Mar 2025 16:41:35 +0000 Allison Henderson wrote: > I think it's to make sure the clearing of the bit is the last > operation done for the calling function, in this case > rds_queue_reconnect. The purpose of the barrier in test_and_set is > to make sure the bit is checked before proceeding to any further > operations (in our case queuing reconnect items). Let's be precise, can you give an example of 2 execution threads and memory accesses which have to be ordered.