From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZph46+pnJFzFkKN+ktJGOzAh8zjwibpmjSrwhBtCHs12zzXkmnhaTYKJ+9Rkxx3dYbendM0 ARC-Seal: i=1; a=rsa-sha256; t=1526631704; cv=none; d=google.com; s=arc-20160816; b=QNVTsb6lTSFvHuC22FN/kD1hYutb7LLuvYAmJt1O9/iQFatzNq/IeNPWE2xhNA6IOi uWOND6oJWSdi7qBb2bq81JPvDa9yUIwQ/W6agxRZMZQLHB1HuUhrl84JdJTi9GzZjgoH JwBHeb5bkwinp3S3KVXMEHzVE7RNMv3Jwtw3ETObS7AhYE3dm67MtliqN8ipWc5Sqn2t Y2/KlSO2VaFzHDp0opR7EXPTg3p3QSOY6ANV3UCIyExw0yu/ECzR1ZoQdVVwh4+5WNj9 8PaqgBnG29iOHtR0Yi5TJoo4ctFSzZU2S3hn0rwhnaO5XpuwA/v+T/Ek9ZNCTOnhT65O ZZHQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=hcOGPC4slWP74H+XFY9diDmv718XUkpyEhd0N+jx9qA=; b=kP0B9sggS/Z3dbkWWptDedyaBQywseupY9lSMpfjZIPSqG1pz/mGFyAAzbhlke4sar +BUs1Ok3DPjck8wMmANYik4RSqIf+MXKzf+MXKDstTSEHQobtmjCYnTVYvFz+l133vpz njfSnHmOHrIH/O7PoQlBnNmCW5LHFsHculwjCSZrrIhoM0I+RrNR7XN89/ROO9MBgiXQ FoS2UzY+F39CJqtV285NsCkLAko6/RCEdP9LK81dIPyszqk0Q/S4/pdAz3fmfN59TWO8 T/dKM0H+Pg5m5HOprOtXOX+HNgPdZiW51/hVgMCvOepr5o3c/imDSgjOw7/44Y4UZvVk RtbQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=zyr5KzZj; spf=pass (google.com: domain of srs0=xuy6=if=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=XuY6=IF=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=zyr5KzZj; spf=pass (google.com: domain of srs0=xuy6=if=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=XuY6=IF=linuxfoundation.org=gregkh@kernel.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neal Cardwell , Yuchung Cheng , Soheil Hassas Yeganeh , Priyaranjan Jha , Yousuk Seung , "David S. Miller" Subject: [PATCH 4.9 18/33] tcp_bbr: fix to zero idle_restart only upon S/ACKed data Date: Fri, 18 May 2018 10:15:57 +0200 Message-Id: <20180518081535.835139233@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180518081535.096308218@linuxfoundation.org> References: <20180518081535.096308218@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1600789108162066793?= X-GMAIL-MSGID: =?utf-8?q?1600789365919914217?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neal Cardwell [ Upstream commit e6e6a278b1eaffa19d42186bfacd1ffc15a50b3f ] Previously the bbr->idle_restart tracking was zeroing out the bbr->idle_restart bit upon ACKs that did not SACK or ACK anything, e.g. receiving incoming data or receiver window updates. In such situations BBR would forget that this was a restart-from-idle situation, and if the min_rtt had expired it would unnecessarily enter PROBE_RTT (even though we were actually restarting from idle but had merely forgotten that fact). The fix is simple: we need to remember we are restarting from idle until we receive a S/ACK for some data (a S/ACK for the first flight of data we send as we are restarting). This commit is a stable candidate for kernels back as far as 4.9. Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control") Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Priyaranjan Jha Signed-off-by: Yousuk Seung Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_bbr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -773,7 +773,9 @@ static void bbr_update_min_rtt(struct so } } } - bbr->idle_restart = 0; + /* Restart after idle ends only once we process a new S/ACK for data */ + if (rs->delivered > 0) + bbr->idle_restart = 0; } static void bbr_update_model(struct sock *sk, const struct rate_sample *rs)