This is a note to let you know that I've just added the patch titled tcp: make challenge acks faster to the 3.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tcp_acks_speedup.patch and it can be found in the queue-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Aug 17 10:00:14 CEST 2016 Date: Wed, 17 Aug 2016 10:00:14 +0200 To: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Subject: tcp: make challenge acks faster From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> When backporting upstream commit 75ff39ccc1bd ("tcp: make challenge acks less predictable") I negelected to use the correct ACCESS* type macros. This fixes that up to hopefully speed things up a bit more. Thanks to Chas Wiliams for the 3.10 backport which reminded me of this. Cc: Yue Cao <ycao009@xxxxxxx> Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Yuchung Cheng <ycheng@xxxxxxxxxx> Cc: Neal Cardwell <ncardwell@xxxxxxxxxx> Cc: Neal Cardwell <ncardwell@xxxxxxxxxx> Cc: Yuchung Cheng <ycheng@xxxxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Chas Williams <ciwillia@xxxxxxxxxxx> Cc: Willy Tarreau <w@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/tcp_input.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3299,12 +3299,12 @@ static void tcp_send_challenge_ack(struc u32 half = (sysctl_tcp_challenge_ack_limit + 1) >> 1; challenge_timestamp = now; - challenge_count = half + + ACCESS_ONCE(challenge_count) = half + prandom_u32_max(sysctl_tcp_challenge_ack_limit); } - count = challenge_count; + count = ACCESS_ONCE(challenge_count); if (count > 0) { - challenge_count = count - 1; + ACCESS_ONCE(challenge_count) = count - 1; NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK); tcp_send_ack(sk); } Patches currently in stable-queue which might be from gregkh@xxxxxxxxxxxxxxxxxxx are queue-3.14/tcp_acks_speedup.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html