Date: Wed, 15 Dec 2021 14:43:08 GMT From: Randall Stewart <rrs@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 9b6029653113 - main - tcp: Rack in a rare case we can get stuck sending a very small amount. Message-ID: <202112151443.1BFEh8Ts064158@gitrepo.freebsd.org>
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The branch main has been updated by rrs: URL: https://cgit.FreeBSD.org/src/commit/?id=9b602965311391f495f4edff246bcb1de5269bbb commit 9b602965311391f495f4edff246bcb1de5269bbb Author: Randall Stewart <rrs@FreeBSD.org> AuthorDate: 2021-12-15 14:41:33 +0000 Commit: Randall Stewart <rrs@FreeBSD.org> CommitDate: 2021-12-15 14:41:33 +0000 tcp: Rack in a rare case we can get stuck sending a very small amount. If a tlp sending new data fails, and then the peer starts talking to us again, we can be in a situation where the tlp_new_data count is set, we are not in recovery and we always send one packet every RTT. The failure has to occur when we send the TLP initially from the ip_output() which is rare. But if it occurs you are basically stuck. This fixes it so we use the new_data count and clear it so we know it will be cleared. If a failure occurs the tlp timer will regenerate a new amount anyway so it is un-needed to carry the value on. Reviewed by: Michael Tuexen Sponsored by: Netflix Inc. Differential Revision: https://reviews.freebsd.org/D33325 --- sys/netinet/tcp_stacks/rack.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c index 16faa887530f..202829f12b7c 100644 --- a/sys/netinet/tcp_stacks/rack.c +++ b/sys/netinet/tcp_stacks/rack.c @@ -17329,6 +17329,7 @@ again: } else { len = rack->r_ctl.rc_tlp_new_data; } + rack->r_ctl.rc_tlp_new_data = 0; } else { len = rack_what_can_we_send(tp, rack, cwnd_to_use, avail, sb_offset); } @@ -18972,10 +18973,6 @@ out: rack->rc_gp_saw_ss = 1; } } - if (doing_tlp && (rsm == NULL)) { - /* Make sure new data TLP cnt is clear */ - rack->r_ctl.rc_tlp_new_data = 0; - } if (TCPS_HAVEESTABLISHED(tp->t_state) && (tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks > 0)
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