From patchwork Tue Jun 4 15:24:12 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 13685599 X-Patchwork-Delegate: kuba@kernel.org Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 250111487DF; Tue, 4 Jun 2024 15:44:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717515893; cv=none; b=shpgB1rfxNOIMmA5LGZCIyyNum5T0vqxSQTLr/DnMLziUCYkqqAPODVrSv+H6rEDS6MZhr0uZ/FnQ8yiPc29X/64eEfAnBC2ZaWBFqtuX/uCOmm0y7DVt4jWG+a/mQVT9kDIVul5ihBXUnxBAbbEGI/okvhXe2prHJwr99wVfIQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717515893; c=relaxed/simple; bh=YiPmxaRADsJsN55xVT2BOQ/1LOJuKBNEnf9YIUI4CIQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kSKSMItjZ/Yp14nVHNDoqwlilVI/P/3tMH6FYbNEcuvCUj35IfBIhOt3MIV/YiLQStr8uO8ONTNU936y4o2q9CqR6zg1Fg25WPvbA60t9O1HcphcMjgwRr/JAE+kJTzAG5gMSn6bWM9C0D3y1hGBzZNMnW3H3hDon28LDrdLMVA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=sYygzvkv; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=yPxC7BH8; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="sYygzvkv"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="yPxC7BH8" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1717515888; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4qaNAKLFhAtWg8AIcUa7hYCunt+INJ3A0lAqwiwMQAI=; b=sYygzvkvuXGawfX4CE9FGBWApWn5wFFD0uTbfXPaZBedk8i1PcvZr1y+3zPgStBSlqD7Qh 8sgt5976MkMpMeMLgDcnzKJhhi/sTrru6pT11YC1BqyV1kYx1vfl6nbQQt/VEq0kiZYyBM 0ONth+PY/r7YyePIImF5zO7NE6sjjsX5xFUnVhSwtynZdr7vVqjwf3SLdsQ0hqV7omT5dM hO8VbFX8uPeMfuopbfDCxuboxhJJjdZb8tlgLQLu93NkuNFy4sZlQkmfNKOUofq/+4DiTY JZskjJmD4FB8lQog/WvargAiMEbu1wfr30AD0LZl6aFgbfHl6Mlq6fTs6ThXrQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1717515888; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4qaNAKLFhAtWg8AIcUa7hYCunt+INJ3A0lAqwiwMQAI=; b=yPxC7BH8RhnqGb/gqn4/oqBnBn0boo0vJ0Fz+w97f8Qcjq1oSN8Xckq/G6DbN4pTrNNCSi zSqzDarDQUfCsCBQ== To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: "David S. Miller" , Daniel Bristot de Oliveira , Boqun Feng , Daniel Borkmann , Eric Dumazet , Frederic Weisbecker , Ingo Molnar , Jakub Kicinski , Paolo Abeni , Peter Zijlstra , Thomas Gleixner , Waiman Long , Will Deacon , Sebastian Andrzej Siewior , David Ahern Subject: [PATCH v4 net-next 05/14] net/ipv4: Use nested-BH locking for ipv4_tcp_sk. Date: Tue, 4 Jun 2024 17:24:12 +0200 Message-ID: <20240604154425.878636-6-bigeasy@linutronix.de> In-Reply-To: <20240604154425.878636-1-bigeasy@linutronix.de> References: <20240604154425.878636-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org ipv4_tcp_sk is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Make a struct with a sock member (original ipv4_tcp_sk) and a local_lock_t and use local_lock_nested_bh() for locking. This change adds only lockdep coverage and does not alter the functional behaviour for !PREEMPT_RT. Cc: David Ahern Signed-off-by: Sebastian Andrzej Siewior --- include/net/sock.h | 5 +++++ net/ipv4/tcp_ipv4.c | 15 +++++++++++---- 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 5f4d0629348f3..365bf676023f8 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -544,6 +544,11 @@ struct sock { netns_tracker ns_tracker; }; +struct sock_bh_locked { + struct sock *sock; + local_lock_t bh_lock; +}; + enum sk_pacing { SK_PACING_NONE = 0, SK_PACING_NEEDED = 1, diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 8f70b8d1d1e56..34c852a4e202d 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -93,7 +93,9 @@ static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key, struct inet_hashinfo tcp_hashinfo; EXPORT_SYMBOL(tcp_hashinfo); -static DEFINE_PER_CPU(struct sock *, ipv4_tcp_sk); +static DEFINE_PER_CPU(struct sock_bh_locked, ipv4_tcp_sk) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; static u32 tcp_v4_init_seq(const struct sk_buff *skb) { @@ -885,7 +887,9 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb, arg.tos = ip_hdr(skb)->tos; arg.uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL); local_bh_disable(); - ctl_sk = this_cpu_read(ipv4_tcp_sk); + local_lock_nested_bh(&ipv4_tcp_sk.bh_lock); + ctl_sk = this_cpu_read(ipv4_tcp_sk.sock); + sock_net_set(ctl_sk, net); if (sk) { ctl_sk->sk_mark = (sk->sk_state == TCP_TIME_WAIT) ? @@ -910,6 +914,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb, sock_net_set(ctl_sk, &init_net); __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); __TCP_INC_STATS(net, TCP_MIB_OUTRSTS); + local_unlock_nested_bh(&ipv4_tcp_sk.bh_lock); local_bh_enable(); #ifdef CONFIG_TCP_MD5SIG @@ -1005,7 +1010,8 @@ static void tcp_v4_send_ack(const struct sock *sk, arg.tos = tos; arg.uid = sock_net_uid(net, sk_fullsock(sk) ? sk : NULL); local_bh_disable(); - ctl_sk = this_cpu_read(ipv4_tcp_sk); + local_lock_nested_bh(&ipv4_tcp_sk.bh_lock); + ctl_sk = this_cpu_read(ipv4_tcp_sk.sock); sock_net_set(ctl_sk, net); ctl_sk->sk_mark = (sk->sk_state == TCP_TIME_WAIT) ? inet_twsk(sk)->tw_mark : READ_ONCE(sk->sk_mark); @@ -1020,6 +1026,7 @@ static void tcp_v4_send_ack(const struct sock *sk, sock_net_set(ctl_sk, &init_net); __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); + local_unlock_nested_bh(&ipv4_tcp_sk.bh_lock); local_bh_enable(); } @@ -3627,7 +3634,7 @@ void __init tcp_v4_init(void) sk->sk_clockid = CLOCK_MONOTONIC; - per_cpu(ipv4_tcp_sk, cpu) = sk; + per_cpu(ipv4_tcp_sk.sock, cpu) = sk; } if (register_pernet_subsys(&tcp_sk_ops)) panic("Failed to create the TCP control socket.\n");