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authorJohannes Berg <johannes@sipsolutions.net>2009-09-12 03:03:15 +0000
committerDavid S. Miller <davem@davemloft.net>2009-09-14 17:02:50 -0700
commitd136f1bd366fdb7e747ca7e0218171e7a00a98a5 (patch)
treecee39b3249c36aba4b765cae6d9d3579c9f10a2d /include
parent8be8057e72d7d319f8e97b26e16de8021fe63988 (diff)
genetlink: fix netns vs. netlink table locking
Since my commits introducing netns awareness into genetlink we can get this problem: BUG: scheduling while atomic: modprobe/1178/0x00000002 2 locks held by modprobe/1178: #0: (genl_mutex){+.+.+.}, at: [<ffffffff8135ee1a>] genl_register_mc_grou #1: (rcu_read_lock){.+.+..}, at: [<ffffffff8135eeb5>] genl_register_mc_g Pid: 1178, comm: modprobe Not tainted 2.6.31-rc8-wl-34789-g95cb731-dirty # Call Trace: [<ffffffff8103e285>] __schedule_bug+0x85/0x90 [<ffffffff81403138>] schedule+0x108/0x588 [<ffffffff8135b131>] netlink_table_grab+0xa1/0xf0 [<ffffffff8135c3a7>] netlink_change_ngroups+0x47/0x100 [<ffffffff8135ef0f>] genl_register_mc_group+0x12f/0x290 because I overlooked that netlink_table_grab() will schedule, thinking it was just the rwlock. However, in the contention case, that isn't actually true. Fix this by letting the code grab the netlink table lock first and then the RCU for netns protection. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/netlink.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 0fbecbbe8e9..080f6ba9e73 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -176,12 +176,16 @@ struct netlink_skb_parms
#define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds)
+extern void netlink_table_grab(void);
+extern void netlink_table_ungrab(void);
+
extern struct sock *netlink_kernel_create(struct net *net,
int unit,unsigned int groups,
void (*input)(struct sk_buff *skb),
struct mutex *cb_mutex,
struct module *module);
extern void netlink_kernel_release(struct sock *sk);
+extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);