From 9b04f350057863d1fad1ba071e09362a1da3503e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 21 Aug 2012 20:48:29 +0000 Subject: ipv4: properly update pmtu Sylvain Munault reported following info : - TCP connection get "stuck" with data in send queue when doing "large" transfers ( like typing 'ps ax' on a ssh connection ) - Only happens on path where the PMTU is lower than the MTU of the interface - Is not present right after boot, it only appears 10-20min after boot or so. (and that's inside the _same_ TCP connection, it works fine at first and then in the same ssh session, it'll get stuck) - Definitely seems related to fragments somehow since I see a router sending ICMP message saying fragmentation is needed. - Exact same setup works fine with kernel 3.5.1 Problem happens when the 10 minutes (ip_rt_mtu_expires) expiration period is over. ip_rt_update_pmtu() calls dst_set_expires() to rearm a new expiration, but dst_set_expires() does nothing because dst.expires is already set. It seems we want to set the expires field to a new value, regardless of prior one. With help from Julian Anastasov. Reported-by: Sylvain Munaut Signed-off-by: Eric Dumazet CC: Julian Anastasov Tested-by: Sylvain Munaut Signed-off-by: David S. Miller --- net/ipv4/route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/route.c') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index fd9ecb52c66b..8c8c748ebb28 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -956,7 +956,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, dst->obsolete = DST_OBSOLETE_KILL; } else { rt->rt_pmtu = mtu; - dst_set_expires(&rt->dst, ip_rt_mtu_expires); + rt->dst.expires = max(1UL, jiffies + ip_rt_mtu_expires); } } -- cgit v1.2.3-58-ga151 From 78df76a065ae3b5dbcb9a29912adc02f697de498 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 24 Aug 2012 05:40:47 +0000 Subject: ipv4: take rt_uncached_lock only if needed Multicast traffic allocates dst with DST_NOCACHE, but dst is not inserted into rt_uncached_list. This slowdown multicast workloads on SMP because rt_uncached_lock is contended. Change the test before taking the lock to actually check the dst was inserted into rt_uncached_list. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/route.c') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8c8c748ebb28..24fd4c596643 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1263,7 +1263,7 @@ static void ipv4_dst_destroy(struct dst_entry *dst) { struct rtable *rt = (struct rtable *) dst; - if (dst->flags & DST_NOCACHE) { + if (!list_empty(&rt->rt_uncached)) { spin_lock_bh(&rt_uncached_lock); list_del(&rt->rt_uncached); spin_unlock_bh(&rt_uncached_lock); -- cgit v1.2.3-58-ga151 From c5ae7d41927dbd208c885d4794e30617ad6cdf12 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 28 Aug 2012 12:33:07 +0000 Subject: ipv4: must use rcu protection while calling fib_lookup Following lockdep splat was reported by Pavel Roskin : [ 1570.586223] =============================== [ 1570.586225] [ INFO: suspicious RCU usage. ] [ 1570.586228] 3.6.0-rc3-wl-main #98 Not tainted [ 1570.586229] ------------------------------- [ 1570.586231] /home/proski/src/linux/net/ipv4/route.c:645 suspicious rcu_dereference_check() usage! [ 1570.586233] [ 1570.586233] other info that might help us debug this: [ 1570.586233] [ 1570.586236] [ 1570.586236] rcu_scheduler_active = 1, debug_locks = 0 [ 1570.586238] 2 locks held by Chrome_IOThread/4467: [ 1570.586240] #0: (slock-AF_INET){+.-...}, at: [] release_sock+0x2c/0xa0 [ 1570.586253] #1: (fnhe_lock){+.-...}, at: [] update_or_create_fnhe+0x2c/0x270 [ 1570.586260] [ 1570.586260] stack backtrace: [ 1570.586263] Pid: 4467, comm: Chrome_IOThread Not tainted 3.6.0-rc3-wl-main #98 [ 1570.586265] Call Trace: [ 1570.586271] [] lockdep_rcu_suspicious+0xfd/0x130 [ 1570.586275] [] update_or_create_fnhe+0x15c/0x270 [ 1570.586278] [] __ip_rt_update_pmtu+0x73/0xb0 [ 1570.586282] [] ip_rt_update_pmtu+0x29/0x90 [ 1570.586285] [] inet_csk_update_pmtu+0x2c/0x80 [ 1570.586290] [] tcp_v4_mtu_reduced+0x2e/0xc0 [ 1570.586293] [] tcp_release_cb+0xa4/0xb0 [ 1570.586296] [] release_sock+0x55/0xa0 [ 1570.586300] [] tcp_sendmsg+0x4af/0xf50 [ 1570.586305] [] inet_sendmsg+0x120/0x230 [ 1570.586308] [] ? inet_sk_rebuild_header+0x40/0x40 [ 1570.586312] [] ? sock_update_classid+0xbd/0x3b0 [ 1570.586315] [] ? sock_update_classid+0x130/0x3b0 [ 1570.586320] [] do_sock_write+0xc5/0xe0 [ 1570.586323] [] sock_aio_write+0x53/0x80 [ 1570.586328] [] do_sync_write+0xa3/0xe0 [ 1570.586332] [] vfs_write+0x165/0x180 [ 1570.586335] [] sys_write+0x45/0x90 [ 1570.586340] [] system_call_fastpath+0x16/0x1b Signed-off-by: Eric Dumazet Reported-by: Pavel Roskin Signed-off-by: David S. Miller --- net/ipv4/route.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'net/ipv4/route.c') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 24fd4c596643..82cf2a722b23 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -934,12 +934,14 @@ static u32 __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) if (mtu < ip_rt_min_pmtu) mtu = ip_rt_min_pmtu; + rcu_read_lock(); if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) { struct fib_nh *nh = &FIB_RES_NH(res); update_or_create_fnhe(nh, fl4->daddr, 0, mtu, jiffies + ip_rt_mtu_expires); } + rcu_read_unlock(); return mtu; } -- cgit v1.2.3-58-ga151 From 98d75c3724f9b37cdfdb85f821e10edcb743959e Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Mon, 27 Aug 2012 06:30:01 +0000 Subject: ipv4: Minor logic clean-up in ipv4_mtu In ipv4_mtu there is some logic where we are testing for a non-zero value and a timer expiration, then setting the value to zero, and then testing if the value is zero we set it to a value based on the dst. Instead of bothering with the extra steps it is easier to just cleanup the logic so that we set it to the dst based value if it is zero or if the timer has expired. Signed-off-by: Alexander Duyck --- net/ipv4/route.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'net/ipv4/route.c') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index d2d1e153e7c4..dc9549b5eb1c 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1134,10 +1134,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst) const struct rtable *rt = (const struct rtable *) dst; unsigned int mtu = rt->rt_pmtu; - if (mtu && time_after_eq(jiffies, rt->dst.expires)) - mtu = 0; - - if (!mtu) + if (!mtu || time_after_eq(jiffies, rt->dst.expires)) mtu = dst_metric_raw(dst, RTAX_MTU); if (mtu && rt_is_output_route(rt)) -- cgit v1.2.3-58-ga151