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 21AFD1DE88F; Tue, 8 Oct 2024 13:12:56 +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=1728393177; cv=none; b=gouPAPrq/7b/hiBeRUBQagQMQnrtutpHgxf/wzluxicRy/MdqTWNe/4cqRH1+EFj0zURFfTI+hcsSgDmMLu8Exz7q+LWNOJGz3heMopF4+81E7szq5CNTTNpV1z3qU/Q1MlePY3OvtqyjjhEFXkBiwCe0rS1aGauvJO8PsFeyCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728393177; c=relaxed/simple; bh=3MFAbxwQEmKE8jRm6WdAtfw4Bt2zU4kPbyBdJKI1384=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sUD97Abkcef6Bc2ShdMKh0Ol4E6yTcUUtJMIcdlj5e/gk0eDVPALeWy/0QdBnvQAr0TwmkIKFyIzcTm2bAiJzR0JsYY17zdEzM6ph24+edcuKdu5k5oLUnTO/RE3U6G8yIDOJ81HVzyOrJoZ6seUqNvTCjGH+N2HKfipVfMcb4E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oBkX6fF8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="oBkX6fF8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36DAAC4CEC7; Tue, 8 Oct 2024 13:12:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728393176; bh=3MFAbxwQEmKE8jRm6WdAtfw4Bt2zU4kPbyBdJKI1384=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oBkX6fF8BrBE3imNnWuiKisKjcoVu7BE+k6rRYr31ZihHjsMvBfCz0gqHhbDQCRUq /HwADiTC5UTxanCcp/9/COmCi3CN66IS7s1lUIFUmoP0z45uDChYOiUuZ505ZoMJ11 UOsn1gpZrLxWZa3tvxULCveaJvS5NGdf1MMkVLbw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vinicius Costa Gomes , Dmitry Antipov , "David S. Miller" , Sasha Levin Subject: [PATCH 6.6 075/386] net: sched: consistently use rcu_replace_pointer() in taprio_change() Date: Tue, 8 Oct 2024 14:05:20 +0200 Message-ID: <20241008115632.412954100@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115629.309157387@linuxfoundation.org> References: <20241008115629.309157387@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Antipov [ Upstream commit d5c4546062fd6f5dbce575c7ea52ad66d1968678 ] According to Vinicius (and carefully looking through the whole https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa once again), txtime branch of 'taprio_change()' is not going to race against 'advance_sched()'. But using 'rcu_replace_pointer()' in the former may be a good idea as well. Suggested-by: Vinicius Costa Gomes Signed-off-by: Dmitry Antipov Acked-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sched/sch_taprio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 418d4a846d04a..87090d6790362 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -1975,7 +1975,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt, goto unlock; } - rcu_assign_pointer(q->admin_sched, new_admin); + /* Not going to race against advance_sched(), but still */ + admin = rcu_replace_pointer(q->admin_sched, new_admin, + lockdep_rtnl_is_held()); if (admin) call_rcu(&admin->rcu, taprio_free_sched_cb); } else { -- 2.43.0