BMC/Intel-BMC/linux.git/net/ipv4/tcp_illinois.c, branch dev

tcp: prepare CC get_info() access from getsockopt()

2015-04-29T21:10:38+00:00

We would like that optional info provided by Congestion Control modules using netlink can also be read using getsockopt() This patch changes get_info() to put this information in a buffer, instead of skb, like tcp_get_info(), so that following patch can reuse this common infrastructure. Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Cc: Neal Cardwell Acked-by: Neal Cardwell Acked-by: Daniel Borkmann Acked-by: Yuchung Cheng Signed-off-by: David S. Miller

inet_diag: fix access to tcp cc information

2015-04-17T17:28:31+00:00

Two different problems are fixed here : 1) inet_sk_diag_fill() might be called without socket lock held. icsk->icsk_ca_ops can change under us and module be unloaded. -> Access to freed memory. Fix this using rcu_read_lock() to prevent module unload. 2) Some TCP Congestion Control modules provide information but again this is not safe against icsk->icsk_ca_ops change and nla_put() errors were ignored. Some sockets could not get the additional info if skb was almost full. Fix this by returning a status from get_info() handlers and using rcu protection as well. Signed-off-by: Eric Dumazet Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

tcp: whitespace fixes

2014-09-02T01:12:45+00:00

Fix places where there is space before tab, long lines, and awkward if(){, double spacing etc. Add blank line after declaration/initialization. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

tcp: remove in_flight parameter from cong_avoid() methods

2014-05-03T23:23:07+00:00

Commit e114a710aa505 ("tcp: fix cwnd limited checking to improve congestion control") obsoleted in_flight parameter from tcp_is_cwnd_limited() and its callers. This patch does the removal as promised. Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller

tcp: switch rtt estimations to usec resolution

2014-02-26T22:08:40+00:00

Upcoming congestion controls for TCP require usec resolution for RTT estimations. Millisecond resolution is simply not enough these days. FQ/pacing in DC environments also require this change for finer control and removal of bimodal behavior due to the current hack in tcp_update_pacing_rate() for 'small rtt' TCP_CONG_RTT_STAMP is no longer needed. As Julian Anastasov pointed out, we need to keep user compatibility : tcp_metrics used to export RTT and RTTVAR in msec resolution, so we added RTT_US and RTTVAR_US. An iproute2 patch is needed to use the new attributes if provided by the kernel. In this example ss command displays a srtt of 32 usecs (10Gbit link) lpk51:~# ./ss -i dst lpk52 Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port tcp ESTAB 0 1 10.246.11.51:42959 10.246.11.52:64614 cubic wscale:6,6 rto:201 rtt:0.032/0.001 ato:40 mss:1448 cwnd:10 send 3620.0Mbps pacing_rate 7240.0Mbps unacked:1 rcv_rtt:993 rcv_space:29559 Updated iproute2 ip command displays : lpk51:~# ./ip tcp_metrics | grep 10.246.11.52 10.246.11.52 age 561.914sec cwnd 10 rtt 274us rttvar 213us source 10.246.11.51 Old binary displays : lpk51:~# ip tcp_metrics | grep 10.246.11.52 10.246.11.52 age 561.914sec cwnd 10 rtt 250us rttvar 125us source 10.246.11.51 With help from Julian Anastasov, Stephen Hemminger and Yuchung Cheng Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Cc: Stephen Hemminger Cc: Yuchung Cheng Cc: Larry Brakmo Cc: Julian Anastasov Signed-off-by: David S. Miller

tcp: remove unused min_cwnd member of tcp_congestion_ops

2014-02-13T23:22:34+00:00

Commit 684bad110757 "tcp: use PRR to reduce cwin in CWR state" removed all calls to min_cwnd, so we can safely remove it. Also, remove tcp_reno_min_cwnd because it was only used for min_cwnd. Signed-off-by: Stanislav Fomichev Acked-by: Yuchung Cheng Signed-off-by: David S. Miller

remove extra definitions of U32_MAX

2014-01-24T00:36:55+00:00

Now that the definition is centralized in , the definitions of U32_MAX (and related) elsewhere in the kernel can be removed. Signed-off-by: Alex Elder Acked-by: Sage Weil Acked-by: David S. Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

conditionally define U32_MAX

2014-01-24T00:36:54+00:00

The symbol U32_MAX is defined in several spots. Change these definitions to be conditional. This is in preparation for the next patch, which centralizes the definition in . Signed-off-by: Alex Elder Cc: Sage Weil Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

tcp: properly handle stretch acks in slow start

2013-11-05T00:57:59+00:00

Slow start now increases cwnd by 1 if an ACK acknowledges some packets, regardless the number of packets. Consequently slow start performance is highly dependent on the degree of the stretch ACKs caused by receiver or network ACK compression mechanisms (e.g., delayed-ACK, GRO, etc). But slow start algorithm is to send twice the amount of packets of packets left so it should process a stretch ACK of degree N as if N ACKs of degree 1, then exits when cwnd exceeds ssthresh. A follow up patch will use the remainder of the N (if greater than 1) to adjust cwnd in the congestion avoidance phase. In addition this patch retires the experimental limited slow start (LSS) feature. LSS has multiple drawbacks but questionable benefit. The fractional cwnd increase in LSS requires a loop in slow start even though it's rarely used. Configuring such an increase step via a global sysctl on different BDPS seems hard. Finally and most importantly the slow start overshoot concern is now better covered by the Hybrid slow start (hystart) enabled by default. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: fix divide by zero in tcp algorithm illinois

2012-11-01T15:55:59+00:00

Reading TCP stats when using TCP Illinois congestion control algorithm can cause a divide by zero kernel oops. The division by zero occur in tcp_illinois_info() at: do_div(t, ca->cnt_rtt); where ca->cnt_rtt can become zero (when rtt_reset is called) Steps to Reproduce: 1. Register tcp_illinois: # sysctl -w net.ipv4.tcp_congestion_control=illinois 2. Monitor internal TCP information via command "ss -i" # watch -d ss -i 3. Establish new TCP conn to machine Either it fails at the initial conn, or else it needs to wait for a loss or a reset. This is only related to reading stats. The function avg_delay() also performs the same divide, but is guarded with a (ca->cnt_rtt > 0) at its calling point in update_params(). Thus, simply fix tcp_illinois_info(). Function tcp_illinois_info() / get_info() is called without socket lock. Thus, eliminate any race condition on ca->cnt_rtt by using a local stack variable. Simply reuse info.tcpv_rttcnt, as its already set to ca->cnt_rtt. Function avg_delay() is not affected by this race condition, as its called with the socket lock. Cc: Petr Matousek Signed-off-by: Jesper Dangaard Brouer Acked-by: Eric Dumazet Acked-by: Stephen Hemminger Signed-off-by: David S. Miller