This is a note to let you know that I've just added the patch titled

tcp: correct memory barrier usage in tcp_check_space()

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: tcp-correct-memory-barrier-usage-in-tcp_check_space.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Dec 6 16:43:17 CET 2017

From: Jason Baron jbaron@akamai.com Date: Tue, 24 Jan 2017 21:49:41 -0500 Subject: tcp: correct memory barrier usage in tcp_check_space()

From: Jason Baron jbaron@akamai.com

[ Upstream commit 56d806222ace4c3aeae516cd7a855340fb2839d8 ]

sock_reset_flag() maps to __clear_bit() not the atomic version clear_bit(). Thus, we need smp_mb(), smp_mb__after_atomic() is not sufficient.

Fixes: 3c7151275c0c ("tcp: add memory barriers to write space paths") Cc: Eric Dumazet eric.dumazet@gmail.com Cc: Oleg Nesterov oleg@redhat.com Signed-off-by: Jason Baron jbaron@akamai.com Acked-by: Eric Dumazet edumazet@google.com Reported-by: Oleg Nesterov oleg@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4942,7 +4942,7 @@ static void tcp_check_space(struct sock if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) { sock_reset_flag(sk, SOCK_QUEUE_SHRUNK); /* pairs with tcp_poll() */ - smp_mb__after_atomic(); + smp_mb(); if (sk->sk_socket && test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) tcp_new_space(sk);

Patches currently in stable-queue which might be from jbaron@akamai.com are

queue-4.4/tcp-correct-memory-barrier-usage-in-tcp_check_space.patch