tcp: Fix race in tcp_poll

2010-12-09T21:24:20Z

[ Upstream commit a4d258036ed9b2a1811c3670c6099203a0f284a0 ] If a RST comes in immediately after checking sk->sk_err, tcp_poll will return POLLIN but not POLLOUT. Fix this by checking sk->sk_err at the end of tcp_poll. Additionally, ensure the correct order of operations on SMP machines with memory barriers. Signed-off-by: Tom Marshall Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: fix >2 iw selection

2009-06-12T03:01:18Z

[ Upstream commit 86bcebafc5e7f5163ccf828792fe694b112ed6fa ] A long-standing feature in tcp_init_metrics() is such that any of its goto reset prevents call to tcp_init_cwnd(). Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: Fix possible double-ack w/ user dma

2008-10-07T22:31:19Z

From: Ali Saidi When TCP receive copy offload is enabled it's possible that tcp_rcv_established() will cause two acks to be sent for a single packet. In the case that a tcp_dma_early_copy() is successful, copied_early is set to true which causes tcp_cleanup_rbuf() to be called early which can send an ack. Further along in tcp_rcv_established(), __tcp_ack_snd_check() is called and will schedule a delayed ACK. If no packets are processed before the delayed ack timer expires the packet will be acked twice. Signed-off-by: David S. Miller

net: convert BUG_TRAP to generic WARN_ON

2008-07-26T04:43:18Z

Removes legacy reinvent-the-wheel type thing. The generic machinery integrates much better to automated debugging aids such as kerneloops.org (and others), and is unambiguous due to better naming. Non-intuively BUG_TRAP() is actually equal to WARN_ON() rather than BUG_ON() though some might actually be promoted to BUG_ON() but I left that to future. I could make at least one BUILD_BUG_ON conversion. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller

tcp: Clear probes_out more aggressively in tcp_ack().

2008-07-23T23:38:45Z

This is based upon an excellent bug report from Eric Dumazet. tcp_ack() should clear ->icsk_probes_out even if there are packets outstanding. Otherwise if we get a sequence of ACKs while we do have packets outstanding over and over again, we'll never clear the probes_out value and eventually think the connection is too sick and we'll reset it. This appears to be some "optimization" added to tcp_ack() in the 2.4.x timeframe. In 2.2.x, probes_out is pretty much always cleared by tcp_ack(). Here is Eric's original report: ---------------------------------------- Apparently, we can in some situations reset TCP connections in a couple of seconds when some frames are lost. In order to reproduce the problem, please try the following program on linux-2.6.25.* Setup some iptables rules to allow two frames per second sent on loopback interface to tcp destination port 12000 iptables -N SLOWLO iptables -A SLOWLO -m hashlimit --hashlimit 2 --hashlimit-burst 1 --hashlimit-mode dstip --hashlimit-name slow2 -j ACCEPT iptables -A SLOWLO -j DROP iptables -A OUTPUT -o lo -p tcp --dport 12000 -j SLOWLO Then run the attached program and see the output : # ./loop State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,1) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,3) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,5) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,7) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,9) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,200ms,11) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,201ms,13) State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 40 127.0.0.1:54455 127.0.0.1:12000 timer:(persist,188ms,15) write(): Connection timed out wrote 890 bytes but was interrupted after 9 seconds ESTAB 0 0 127.0.0.1:12000 127.0.0.1:54455 Exiting read() because no data available (4000 ms timeout). read 860 bytes While this tcp session makes progress (sending frames with 50 bytes of payload, every 500ms), linux tcp stack decides to reset it, when tcp_retries 2 is reached (default value : 15) tcpdump : 15:30:28.856695 IP 127.0.0.1.56554 > 127.0.0.1.12000: S 33788768:33788768(0) win 32792 15:30:28.856711 IP 127.0.0.1.12000 > 127.0.0.1.56554: S 33899253:33899253(0) ack 33788769 win 32792 15:30:29.356947 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 1:61(60) ack 1 win 257 15:30:29.356966 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 61 win 257 15:30:29.866415 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 61:111(50) ack 1 win 257 15:30:29.866427 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 111 win 257 15:30:30.366516 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 111:161(50) ack 1 win 257 15:30:30.366527 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 161 win 257 15:30:30.876196 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 161:211(50) ack 1 win 257 15:30:30.876207 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 211 win 257 15:30:31.376282 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 211:261(50) ack 1 win 257 15:30:31.376290 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 261 win 257 15:30:31.885619 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 261:311(50) ack 1 win 257 15:30:31.885631 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 311 win 257 15:30:32.385705 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 311:361(50) ack 1 win 257 15:30:32.385715 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 361 win 257 15:30:32.895249 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 361:411(50) ack 1 win 257 15:30:32.895266 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 411 win 257 15:30:33.395341 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 411:461(50) ack 1 win 257 15:30:33.395351 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 461 win 257 15:30:33.918085 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 461:511(50) ack 1 win 257 15:30:33.918096 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 511 win 257 15:30:34.418163 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 511:561(50) ack 1 win 257 15:30:34.418172 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 561 win 257 15:30:34.927685 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 561:611(50) ack 1 win 257 15:30:34.927698 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 611 win 257 15:30:35.427757 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 611:661(50) ack 1 win 257 15:30:35.427766 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 661 win 257 15:30:35.937359 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 661:711(50) ack 1 win 257 15:30:35.937376 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 711 win 257 15:30:36.437451 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 711:761(50) ack 1 win 257 15:30:36.437464 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 761 win 257 15:30:36.947022 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 761:811(50) ack 1 win 257 15:30:36.947039 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 811 win 257 15:30:37.447135 IP 127.0.0.1.56554 > 127.0.0.1.12000: P 811:861(50) ack 1 win 257 15:30:37.447203 IP 127.0.0.1.12000 > 127.0.0.1.56554: . ack 861 win 257 15:30:41.448171 IP 127.0.0.1.12000 > 127.0.0.1.56554: F 1:1(0) ack 861 win 257 15:30:41.448189 IP 127.0.0.1.56554 > 127.0.0.1.12000: R 33789629:33789629(0) win 0 Source of program : /* * small producer/consumer program. * setup a listener on 127.0.0.1:12000 * Forks a child * child connect to 127.0.0.1, and sends 10 bytes on this tcp socket every 100 ms * Father accepts connection, and read all data */ #include #include #include #include #include #include #include int port = 12000; char buffer[4096]; int main(int argc, char *argv[]) { int lfd = socket(AF_INET, SOCK_STREAM, 0); struct sockaddr_in socket_address; time_t t0, t1; int on = 1, sfd, res; unsigned long total = 0; socklen_t alen = sizeof(socket_address); pid_t pid; time(&t0); socket_address.sin_family = AF_INET; socket_address.sin_port = htons(port); socket_address.sin_addr.s_addr = htonl(INADDR_LOOPBACK); if (lfd == -1) { perror("socket()"); return 1; } setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(int)); if (bind(lfd, (struct sockaddr *)&socket_address, sizeof(socket_address)) == -1) { perror("bind"); close(lfd); return 1; } if (listen(lfd, 1) == -1) { perror("listen()"); close(lfd); return 1; } pid = fork(); if (pid == 0) { int i, cfd = socket(AF_INET, SOCK_STREAM, 0); close(lfd); if (connect(cfd, (struct sockaddr *)&socket_address, sizeof(socket_address)) == -1) { perror("connect()"); return 1; } for (i = 0 ; ;) { res = write(cfd, "blablabla\n", 10); if (res > 0) total += res; else if (res == -1) { perror("write()"); break; } else break; usleep(100000); if (++i == 10) { system("ss -on dst 127.0.0.1:12000"); i = 0; } } time(&t1); fprintf(stderr, "wrote %lu bytes but was interrupted after %g seconds\n", total, difftime(t1, t0)); system("ss -on | grep 127.0.0.1:12000"); close(cfd); return 0; } sfd = accept(lfd, (struct sockaddr *)&socket_address, &alen); if (sfd == -1) { perror("accept"); return 1; } close(lfd); while (1) { struct pollfd pfd[1]; pfd[0].fd = sfd; pfd[0].events = POLLIN; if (poll(pfd, 1, 4000) == 0) { fprintf(stderr, "Exiting read() because no data available (4000 ms timeout).\n"); break; } res = read(sfd, buffer, sizeof(buffer)); if (res > 0) total += res; else if (res == 0) break; else perror("read()"); } fprintf(stderr, "read %lu bytes\n", total); close(sfd); return 0; } ---------------------------------------- Signed-off-by: David S. Miller

tcp: Remove redundant checks when setting eff_sacks

2008-07-19T07:07:02Z

Remove redundant checks when setting eff_sacks and make the number of SACKs a compile time constant. Now that the options code knows how many SACK blocks can fit in the header, we don't need to have the SACK code guessing at it. Signed-off-by: Adam Langley Signed-off-by: David S. Miller

tcp: RTT metrics scaling

2008-07-19T06:02:15Z

Some of the metrics (RTT, RTTVAR and RTAX_RTO_MIN) are stored in kernel units (jiffies) and this leaks out through the netlink API to user space where the units for jiffies are unknown. This patches changes the kernel to convert to/from milliseconds. This changes the ABI, but milliseconds seemed like the most natural unit for these parameters. Values available via syscall in /proc/net/rt_cache and netlink will be in milliseconds. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

mib: add net to NET_INC_STATS_BH

2008-07-17T03:31:16Z

Signed-off-by: Pavel Emelyanov Signed-off-by: David S. Miller

tcp: replace tcp_sock argument with sock in some places

2008-07-17T03:29:51Z

These places have a tcp_sock, but we'd prefer the sock itself to get net from it. Fortunately, tcp_sk macro is just a type cast, so this replace is really cheap. Signed-off-by: Pavel Emelyanov Signed-off-by: David S. Miller

mib: add net to TCP_INC_STATS_BH

2008-07-17T03:22:25Z

Same as before - the sock is always there to get the net from, but there are also some places with the net already saved on the stack. Signed-off-by: Pavel Emelyanov Signed-off-by: David S. Miller

kernel.git/net/ipv4/tcp_input.c, branch linux-2.6.27.y