linux/include/net/netns
Pavel Emelyanov 0fa7fa98db packet: Protect packet sk list with mutex (v2)
Change since v1:

* Fixed inuse counters access spotted by Eric

In patch eea68e2f (packet: Report socket mclist info via diag module) I've
introduced a "scheduling in atomic" problem in packet diag module -- the
socket list is traversed under rcu_read_lock() while performed under it sk
mclist access requires rtnl lock (i.e. -- mutex) to be taken.

[152363.820563] BUG: scheduling while atomic: crtools/12517/0x10000002
[152363.820573] 4 locks held by crtools/12517:
[152363.820581]  #0:  (sock_diag_mutex){+.+.+.}, at: [<ffffffff81a2dcb5>] sock_diag_rcv+0x1f/0x3e
[152363.820613]  #1:  (sock_diag_table_mutex){+.+.+.}, at: [<ffffffff81a2de70>] sock_diag_rcv_msg+0xdb/0x11a
[152363.820644]  #2:  (nlk->cb_mutex){+.+.+.}, at: [<ffffffff81a67d01>] netlink_dump+0x23/0x1ab
[152363.820693]  #3:  (rcu_read_lock){.+.+..}, at: [<ffffffff81b6a049>] packet_diag_dump+0x0/0x1af

Similar thing was then re-introduced by further packet diag patches (fanount
mutex and pgvec mutex for rings) :(

Apart from being terribly sorry for the above, I propose to change the packet
sk list protection from spinlock to mutex. This lock currently protects two
modifications:

* sklist
* prot inuse counters

The sklist modifications can be just reprotected with mutex since they already
occur in a sleeping context. The inuse counters modifications are trickier -- the
__this_cpu_-s are used inside, thus requiring the caller to handle the potential
issues with contexts himself. Since packet sockets' counters are modified in two
places only (packet_create and packet_release) we only need to protect the context
from being preempted. BH disabling is not required in this case.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-08-22 22:58:27 -07:00
..
conntrack.h netfilter: nf_ct_icmp: add namespace support 2012-06-07 14:58:40 +02:00
core.h percpu: add __percpu sparse annotations to net 2010-02-16 23:05:38 -08:00
dccp.h [NETNS][DCCPV6]: Move the dccp_v6_ctl_sk on the struct net. 2008-04-13 22:32:25 -07:00
generic.h BUG: headers with BUG/BUG_ON etc. need linux/bug.h 2012-03-04 17:54:34 -05:00
hash.h net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
ipv4.h ipv4: remove rt_cache_rebuild_count 2012-07-30 14:53:22 -07:00
ipv6.h inetpeer: add namespace support for inetpeer 2012-06-08 14:27:23 -07:00
mib.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
packet.h packet: Protect packet sk list with mutex (v2) 2012-08-22 22:58:27 -07:00
sctp.h sctp: Make sysctl tunables per net 2012-08-14 23:32:16 -07:00
unix.h
x_tables.h net, netns_xt: shrink netns_xt members 2009-07-05 19:16:18 -07:00
xfrm.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00