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 2890513D61B; Wed, 3 Jul 2024 11:01:23 +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=1720004483; cv=none; b=EWj7mSRONcnBa2cEwYoujwKsVH4NUYcM6hwbz3ZKf6W5WtA1Xa++E0KQRRTWI06+SQq+GrjZz3HKBwOdG4VKSdvngCzjYAehIQSbugw7KvvrjM7JTCPlSEAsq07gEZ7iV5yf4e2UVuzMdOx/HKV8oWRQsW6rR0eGeoN3nhHSaFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720004483; c=relaxed/simple; bh=t/JoExFEz64BisJjCnD9ZLnnXqPCwWcfaQ/iiBlo4ew=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kxDYGkHRSPu58yBiFckpFZi4RCW/m6Exr2bnvXPMTS1RUkjjJukKfE8gloqDLr3qCSkAflZiGzOjxArM0wdtbRYGZPBEcnuKsnumIQ0lYZRF4co4bcj6Mo0DX8mFSYCkNIvnuXnlTt8XAxwsqiUsplEBMTfOHV6rX+KFCkKn0Xc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cZKZ40T3; 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="cZKZ40T3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1E88C2BD10; Wed, 3 Jul 2024 11:01:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720004483; bh=t/JoExFEz64BisJjCnD9ZLnnXqPCwWcfaQ/iiBlo4ew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cZKZ40T3CyWmxP0USwtH1qm847pz7F6EEQss9M2KGgZ41GXhtH3ujLxEtGdpcszqZ IZLUOBpY6XHFPTUPR102if1/xUsUuitZ3BZQ6tzqCRaG9CFWRuGcB0FHwAoZh8aBmp ymAtNYsUDlSuC6FOqrAARevSFYrqIuNE3qiIbPKM= 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 5.10 025/290] af_unix: Use unix_recvq_full_lockless() in unix_stream_connect(). Date: Wed, 3 Jul 2024 12:36:46 +0200 Message-ID: <20240703102905.143015357@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102904.170852981@linuxfoundation.org> References: <20240703102904.170852981@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 5.10-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 f1a9b3759d462..dff75de9de7de 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -189,15 +189,9 @@ 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) @@ -1310,7 +1304,7 @@ 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