From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9731C32772 for ; Tue, 23 Aug 2022 09:36:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351282AbiHWJfW (ORCPT ); Tue, 23 Aug 2022 05:35:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351140AbiHWJei (ORCPT ); Tue, 23 Aug 2022 05:34:38 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF11F956BC; Tue, 23 Aug 2022 01:39:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2042461485; Tue, 23 Aug 2022 08:38:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 100A4C433C1; Tue, 23 Aug 2022 08:38:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661243896; bh=UCYycxyPUwO1hHOBKfBA1QUnk84cOVlOhcqdGlDU2ck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aeA8avaasroYimosAlrL+L5iAk+pw1/BuKYDX9Z1o2Pj6pmw8XjtPFMcFrL8Q8nd8 4e9hPq/qdVTZ7zI85zcdlkKN4cXmnNaLDkctQkoGAZ2btWPigO3t1DMrWrbHthGeUt s3RufXuc87Py9Ctc+MCCcyhUS+zjqv3qGQQmtNNY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , "David S. Miller" Subject: [PATCH 5.15 005/244] rds: add missing barrier to release_refill Date: Tue, 23 Aug 2022 10:22:44 +0200 Message-Id: <20220823080059.271888385@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080059.091088642@linuxfoundation.org> References: <20220823080059.091088642@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikulas Patocka commit 9f414eb409daf4f778f011cf8266d36896bb930b upstream. The functions clear_bit and set_bit do not imply a memory barrier, thus it may be possible that the waitqueue_active function (which does not take any locks) is moved before clear_bit and it could miss a wakeup event. Fix this bug by adding a memory barrier after clear_bit. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/rds/ib_recv.c | 1 + 1 file changed, 1 insertion(+) --- a/net/rds/ib_recv.c +++ b/net/rds/ib_recv.c @@ -363,6 +363,7 @@ static int acquire_refill(struct rds_con static void release_refill(struct rds_connection *conn) { clear_bit(RDS_RECV_REFILL, &conn->c_flags); + smp_mb__after_atomic(); /* We don't use wait_on_bit()/wake_up_bit() because our waking is in a * hot path and finding waiters is very rare. We don't want to walk