From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 59EE950B8A8; Wed, 30 Sep 2026 16:18:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785118; cv=none; b=i4hM27epIJha57nPHc2GoE2ES7JP3W8ZM7dNaFaXq6u0ZOxG6K7AGX1NVWElZs1f7INVDFb5EaPmEotKam9tWDEXZHkmSlPN+r7uaK/1fILSUET0WyZQnuNCMXbm/v36kvUJVCORM7D8SyW5YYn7XuUOFFig5V5cqE+uYlqbw9s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790785118; c=relaxed/simple; bh=MwE3erRS2wzC0p16uJmt6BYr6uJkkTC7Uk2eFPPj1U0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DOqbhMEosDYlOM4Cssl31y03Yirri32I11UwVIUF6B0B7LIKFrW6DJbu6moRaUl7hqywdgOLsZgY+VIfzwgjcLE4SL53WW2N3tv5HxnpqxcBItZepiw3UOJLJKrtu80tXmglmeSA3uas7rnyX4ydGEY1kp3Xnt6niOugaJ3M718= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vb65T9Rz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vb65T9Rz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81F8A1F000FF; Wed, 30 Sep 2026 16:18:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790785113; bh=6u9qweoYUrQZYU0a9v6kdM+xcwtPeb5q30CewveqMz8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=vb65T9RzhTZGLi0dsJN7ATpmf3CM8rVgb0EZ74541Af5cPBtPdWFf5BYl+8c0t0e1 QPiEni1GjICgAOBcXbllgtAmEDpRWktEVOTY3gyI5w0vmzgUVcTR/ogdl+qFXPf7Hq lhuEQjq/sRIKvAnF11cTAAdnwpSOWHWkaUe8/Qt8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Allison Henderson , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 392/982] net/rds: clear cp_flags bits individually in rds_conn_path_reset() Date: Wed, 30 Sep 2026 17:18:48 +0200 Message-ID: <20260930152425.227507659@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Allison Henderson [ Upstream commit 103c4b13c4f50322910078d1c02f29334a574122 ] rds_conn_path_reset() wipes the whole flag word with a plain cp->cp_flags = 0 store. Every other accessor of that word uses atomic bitops, and some of them can run concurrently with the reset: RDS_LL_SEND_FULL is set from rds_send_xmit() and cleared from the transport completion paths, neither of which holds anything that excludes the shutdown worker. A plain store racing an atomic read-modify-write on the same word is a data race, and whichever side loses has its update silently discarded. Clear the two bits the reset is actually responsible for instead. RDS_IN_XMIT and RDS_RECV_REFILL need no store at all here: they belong to the caller, rds_conn_shutdown(), which waits for both to be clear before calling the transport shutdown and this reset. This also gives every bit in cp_flags a single well-defined writer discipline, which the following patches rely on when they turn RDS_IN_XMIT and RDS_RECV_REFILL into bit locks held across the teardown: a blanket store mid-teardown would destroy lock ownership that an atomic clear preserves. Oracle UEK carries the same conversion ("net/rds: Preserve essential connection state flags"), motivated by its asynchronous shutdown state machine, whose progress and destroy flags must survive the reset. UEK's variant also clears RDS_IN_XMIT and RDS_RECV_REFILL because there the reset runs as the final step of a teardown that owns both bits, making those clears its unlock. Upstream that release belongs in rds_conn_shutdown(): once a later patch in this series turns the two bits into locks held across the teardown, ending ownership needs release semantics and a wake-up that a plain clear inside the reset would not provide. Based on Oracle UEK commit "net/rds: Preserve essential connection state flags" by Gerd Rausch. Fixes: 00e0f34c6166 ("RDS: Connection handling") Signed-off-by: Allison Henderson Link: https://patch.msgid.link/20260828223921.202913-4-achender@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/rds/connection.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/rds/connection.c b/net/rds/connection.c index beecd408e93ab..9e0c89b7bc4cd 100644 --- a/net/rds/connection.c +++ b/net/rds/connection.c @@ -119,7 +119,15 @@ static void rds_conn_path_reset(struct rds_conn_path *cp) rds_stats_inc(s_conn_reset); rds_send_path_reset(cp); - cp->cp_flags = 0; + + /* Clear the bits the reset is responsible for individually: a + * blanket cp_flags = 0 is a plain store that can clobber a + * concurrent atomic read-modify-write on the same word. + * RDS_IN_XMIT and RDS_RECV_REFILL belong to the caller, + * rds_conn_shutdown(), and are left alone here. + */ + clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags); + clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags); /* Do not clear next_rx_seq here, else we cannot distinguish * retransmitted packets from new packets, and will hand all -- 2.53.0