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 A39621799F; Wed, 3 Jul 2024 11:14:49 +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=1720005289; cv=none; b=BnCQllHOASUUYcxeuN3UAqepQlhM3x4C3TJ2A2akFf2eWeEBtop1q6k8gD3j7BbWoXXheOIudToC5TGochUnJjEEf+963MQHKE7+OGTRAa2Hk6wn5NZgmS3UySMCfgULz2dAIJLbl98AVuKlgIh4yvw31c9ocljG21tfoYAmsI8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005289; c=relaxed/simple; bh=6Cj2EfDIIqOvp0uObEC60ksS4Ccb5hTbhSQrHuYlSDM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=m4vxGuo9Dbfa+L6rlKNlv0SEHAGlTRQd3Cji+K/a+JiiEAv9gj38UB/3XBuLyN0NU5VkLbWTXvovYj+ZVde4IsY0a1tbvQQnY4dPzZpcouJ+bp/ZX0AvuonrH9JQYFKiYBWLhUuthdYibA2Vve7DAlr65RzzepG17lKrjKZs1W0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FbgzFVUH; 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="FbgzFVUH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BAE6DC2BD10; Wed, 3 Jul 2024 11:14:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720005289; bh=6Cj2EfDIIqOvp0uObEC60ksS4Ccb5hTbhSQrHuYlSDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FbgzFVUHz6OOg79P7nmWlGG9FiXTB2MetWMmAvuA2oaQWuNsuLhpxz8M94UpQlrld rq7k9YfXVbX3y7OY10BbZItC6HNiN4LAb0jb5H5Ib1OPLxxQG0ppgJMdwr3X3z6qFi YM2EwSZzz7ISYXwu7VZzOXzBP2CqMX5/t1nDhoUA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15 031/356] af_unix: Use unix_recvq_full_lockless() in unix_stream_connect(). Date: Wed, 3 Jul 2024 12:36:07 +0200 Message-ID: <20240703102914.275880846@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102913.093882413@linuxfoundation.org> References: <20240703102913.093882413@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 45d872f0e65593176d880ec148f41ad7c02e40a7 ] Once sk->sk_state is changed to TCP_LISTEN, it never changes. unix_accept() takes advantage of this characteristics; it does not hold the listener's unix_state_lock() and only acquires recvq lock to pop one skb. It means unix_state_lock() does not prevent the queue length from changing in unix_stream_connect(). Thus, we need to use unix_recvq_full_lockless() to avoid data-race. Now we remove unix_recvq_full() as no one uses it. Note that we can remove READ_ONCE() for sk->sk_max_ack_backlog in unix_recvq_full_lockless() because of the following reasons: (1) For SOCK_DGRAM, it is a written-once field in unix_create1() (2) For SOCK_STREAM and SOCK_SEQPACKET, it is changed under the listener's unix_state_lock() in unix_listen(), and we hold the lock in unix_stream_connect() Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/unix/af_unix.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -190,15 +190,9 @@ static inline int unix_may_send(struct s return unix_peer(osk) == NULL || unix_our_peer(sk, osk); } -static inline int unix_recvq_full(const struct sock *sk) -{ - return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; -} - static inline int unix_recvq_full_lockless(const struct sock *sk) { - return skb_queue_len_lockless(&sk->sk_receive_queue) > - READ_ONCE(sk->sk_max_ack_backlog); + return skb_queue_len_lockless(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; } struct sock *unix_peer_get(struct sock *s) @@ -1387,7 +1381,7 @@ restart: if (other->sk_shutdown & RCV_SHUTDOWN) goto out_unlock; - if (unix_recvq_full(other)) { + if (unix_recvq_full_lockless(other)) { err = -EAGAIN; if (!timeo) goto out_unlock;