netdev - [RFC net-next 1/4] tcp: no longer release socket ownership in tcp_release

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Message-ID: <20230906201046.463236-2-edumazet@google.com>
Date: Wed,  6 Sep 2023 20:10:43 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Soheil Hassas Yeganeh <soheil@...gle.com>, Neal Cardwell <ncardwell@...gle.com>, 
	Yuchung Cheng <ycheng@...gle.com>, Eric Dumazet <edumazet@...gle.com>
Subject: [RFC net-next 1/4] tcp: no longer release socket ownership in tcp_release_cb()

This partially reverts c3f9b01849ef ("tcp: tcp_release_cb()
should release socket ownership").

prequeue has been removed by Florian in commit e7942d0633c4
("tcp: remove prequeue support")

__tcp_checksum_complete_user() being gone, we no longer
have to release socket ownership in tcp_release_cb().

This is a prereq for third patch in the series
("net: call prot->release_cb() when processing backlog").

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/sock.c       |  3 ---
 net/ipv4/tcp_output.c | 10 ----------
 2 files changed, 13 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 16584e2dd6481a3fc28d796db785439f0446703b..21610e3845a5042f7c648ccb3e0d90126df20a0b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3519,9 +3519,6 @@ void release_sock(struct sock *sk)
 	if (sk->sk_backlog.tail)
 		__release_sock(sk);
 
-	/* Warning : release_cb() might need to release sk ownership,
-	 * ie call sock_release_ownership(sk) before us.
-	 */
 	if (sk->sk_prot->release_cb)
 		sk->sk_prot->release_cb(sk);
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ccfc8bbf745586cd23dcf02d755d6981dc92742e..b4cac12d0e6348aaa3a3957b0091ea7fe6553731 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1101,16 +1101,6 @@ void tcp_release_cb(struct sock *sk)
 		tcp_tsq_write(sk);
 		__sock_put(sk);
 	}
-	/* Here begins the tricky part :
-	 * We are called from release_sock() with :
-	 * 1) BH disabled
-	 * 2) sk_lock.slock spinlock held
-	 * 3) socket owned by us (sk->sk_lock.owned == 1)
-	 *
-	 * But following code is meant to be called from BH handlers,
-	 * so we should keep BH disabled, but early release socket ownership
-	 */
-	sock_release_ownership(sk);
 
 	if (flags & TCPF_WRITE_TIMER_DEFERRED) {
 		tcp_write_timer_handler(sk);
-- 
2.42.0.283.g2d96d420d3-goog