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 050D817B4FF; Wed, 3 Jul 2024 10:42:12 +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=1720003332; cv=none; b=j1gNq5wpqOpOkgE0p9dW+IidNhR1nA1SEzwguyTswfZggKjdEd0Ya2QIW2oa0zjea4j8QmuR8Kmo6Zt1qMSN9q03GfbLXjlAms1svAjbD3T4VC0bFADSSRVn1BdlgS7mtmyu5nMoWjPcswJx2ft3c5BM3aOq56fuuOTwi3Fu38o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720003332; c=relaxed/simple; bh=CYnSKYLUpaWSMm5doIJs3+rsN+8vFlzZDjPChQMzetg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pjtRsakBcRyTBnrJvhdVyvKg3DL+kjs01QSM5Y/T0UcLbhZqli88yccRflx8o9CieitlnRWWOZCBoHVHHrt7RtwK6Q2iHWDGGu7KBPK7bF0iZfqaJJYTMLrCofYPxiPcDxjDl1AtI8yYlOKeXZN8sCsCsaRfvNI9AppzN0cemlg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=b+rx9M01; 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="b+rx9M01" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73D78C2BD10; Wed, 3 Jul 2024 10:42:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720003331; bh=CYnSKYLUpaWSMm5doIJs3+rsN+8vFlzZDjPChQMzetg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b+rx9M01ae5HPRnnjCyeKNvcBzjHa4fSbRDZfvOQSQcKzZG+qI8ssf4f750qqGGKw 9FYO2ZqLzAipZVubHgUNllTFraAR9aEccXCxyZ2f0uVBP/dUEZla6yxXtQo8VDwo/d +JjGrAu7Kpd0npxiJ8ycGV3RoPI9Hn8XH+nTjHXg= 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 4.19 014/139] af_unix: Use unix_recvq_full_lockless() in unix_stream_connect(). Date: Wed, 3 Jul 2024 12:38:31 +0200 Message-ID: <20240703102830.977058578@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102830.432293640@linuxfoundation.org> References: <20240703102830.432293640@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 4.19-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(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4a4b6d2544534..dfcafbb8cd0e0 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -194,15 +194,9 @@ static inline int unix_may_send(struct sock *sk, struct sock *osk) 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) @@ -1306,7 +1300,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, 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; -- 2.43.0