Files
kernel/include/linux
Eric Dumazet d654976cbf tcp: fix a potential deadlock in tcp_get_info()
Taking socket spinlock in tcp_get_info() can deadlock, as
inet_diag_dump_icsk() holds the &hashinfo->ehash_locks[i],
while packet processing can use the reverse locking order.

We could avoid this locking for TCP_LISTEN states, but lockdep would
certainly get confused as all TCP sockets share same lockdep classes.

[  523.722504] ======================================================
[  523.728706] [ INFO: possible circular locking dependency detected ]
[  523.734990] 4.1.0-dbg-DEV #1676 Not tainted
[  523.739202] -------------------------------------------------------
[  523.745474] ss/18032 is trying to acquire lock:
[  523.750002]  (slock-AF_INET){+.-...}, at: [<ffffffff81669d44>] tcp_get_info+0x2c4/0x360
[  523.758129]
[  523.758129] but task is already holding lock:
[  523.763968]  (&(&hashinfo->ehash_locks[i])->rlock){+.-...}, at: [<ffffffff816bcb75>] inet_diag_dump_icsk+0x1d5/0x6c0
[  523.774661]
[  523.774661] which lock already depends on the new lock.
[  523.774661]
[  523.782850]
[  523.782850] the existing dependency chain (in reverse order) is:
[  523.790326]
-> #1 (&(&hashinfo->ehash_locks[i])->rlock){+.-...}:
[  523.796599]        [<ffffffff811126bb>] lock_acquire+0xbb/0x270
[  523.802565]        [<ffffffff816f5868>] _raw_spin_lock+0x38/0x50
[  523.808628]        [<ffffffff81665af8>] __inet_hash_nolisten+0x78/0x110
[  523.815273]        [<ffffffff816819db>] tcp_v4_syn_recv_sock+0x24b/0x350
[  523.822067]        [<ffffffff81684d41>] tcp_check_req+0x3c1/0x500
[  523.828199]        [<ffffffff81682d09>] tcp_v4_do_rcv+0x239/0x3d0
[  523.834331]        [<ffffffff816842fe>] tcp_v4_rcv+0xa8e/0xc10
[  523.840202]        [<ffffffff81658fa3>] ip_local_deliver_finish+0x133/0x3e0
[  523.847214]        [<ffffffff81659a9a>] ip_local_deliver+0xaa/0xc0
[  523.853440]        [<ffffffff816593b8>] ip_rcv_finish+0x168/0x5c0
[  523.859624]        [<ffffffff81659db7>] ip_rcv+0x307/0x420

Lets use u64_sync infrastructure instead. As a bonus, 64bit
arches get optimized, as these are nop for them.

Fixes: 0df48c26d8 ("tcp: add tcpi_bytes_acked to tcp_info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-22 13:46:06 -04:00
..
2015-03-29 16:17:10 +01:00
2015-04-07 11:17:34 +02:00
2015-03-25 20:28:11 -04:00
2015-04-17 09:03:53 -04:00
2015-05-04 13:09:55 -06:00
2015-04-17 08:31:12 -06:00
2015-03-11 15:56:59 -07:00
2015-04-16 12:33:51 +09:30
2015-03-02 16:43:41 -05:00
2015-03-16 21:45:54 +11:00
2015-04-03 16:18:02 +02:00
2015-04-14 16:49:05 -07:00
2015-03-25 11:44:52 +01:00
2015-04-17 09:04:07 -04:00
2015-03-31 12:04:12 +02:00
2015-04-23 14:36:28 -04:00
2015-03-11 17:56:28 -04:00
2015-04-12 21:03:31 +02:00
2015-02-24 08:44:16 +01:00
2015-03-26 18:18:20 +01:00
2015-04-25 15:49:49 -04:00
2015-03-11 21:55:28 -04:00
2015-04-11 15:53:35 -04:00
2015-03-25 13:28:58 +01:00
2015-04-11 22:29:44 -04:00
2015-03-24 09:48:14 -07:00
2015-04-15 16:35:20 -07:00