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authorEric Dumazet <edumazet@google.com>2012-08-28 12:33:07 +0000
committerDavid S. Miller <davem@davemloft.net>2012-08-30 13:33:08 -0400
commitc5ae7d41927dbd208c885d4794e30617ad6cdf12 (patch)
treeaa172acd3759bbcd191dac36336d1a6f123139a7 /net/ipv4
parent5c879d2094946081af934739850c7260e8b25d3c (diff)
downloadlinux-c5ae7d41927dbd208c885d4794e30617ad6cdf12.tar.bz2
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: [<ffffffff814f2c0c>] release_sock+0x2c/0xa0 [ 1570.586253] #1: (fnhe_lock){+.-...}, at: [<ffffffff815302fc>] 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] [<ffffffff810976ed>] lockdep_rcu_suspicious+0xfd/0x130 [ 1570.586275] [<ffffffff8153042c>] update_or_create_fnhe+0x15c/0x270 [ 1570.586278] [<ffffffff815305b3>] __ip_rt_update_pmtu+0x73/0xb0 [ 1570.586282] [<ffffffff81530619>] ip_rt_update_pmtu+0x29/0x90 [ 1570.586285] [<ffffffff815411dc>] inet_csk_update_pmtu+0x2c/0x80 [ 1570.586290] [<ffffffff81558d1e>] tcp_v4_mtu_reduced+0x2e/0xc0 [ 1570.586293] [<ffffffff81553bc4>] tcp_release_cb+0xa4/0xb0 [ 1570.586296] [<ffffffff814f2c35>] release_sock+0x55/0xa0 [ 1570.586300] [<ffffffff815442ef>] tcp_sendmsg+0x4af/0xf50 [ 1570.586305] [<ffffffff8156fc60>] inet_sendmsg+0x120/0x230 [ 1570.586308] [<ffffffff8156fb40>] ? inet_sk_rebuild_header+0x40/0x40 [ 1570.586312] [<ffffffff814f4bdd>] ? sock_update_classid+0xbd/0x3b0 [ 1570.586315] [<ffffffff814f4c50>] ? sock_update_classid+0x130/0x3b0 [ 1570.586320] [<ffffffff814ec435>] do_sock_write+0xc5/0xe0 [ 1570.586323] [<ffffffff814ec4a3>] sock_aio_write+0x53/0x80 [ 1570.586328] [<ffffffff8114bc83>] do_sync_write+0xa3/0xe0 [ 1570.586332] [<ffffffff8114c5a5>] vfs_write+0x165/0x180 [ 1570.586335] [<ffffffff8114c805>] sys_write+0x45/0x90 [ 1570.586340] [<ffffffff815d2722>] system_call_fastpath+0x16/0x1b Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Pavel Roskin <proski@gnu.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/route.c2
1 files changed, 2 insertions, 0 deletions
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;
}