netdev - Re: [PATCH] genetlink: fix netns vs. netlink table locking (2)

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Date:	Thu, 24 Sep 2009 15:45:44 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	johannes@...solutions.net
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] genetlink: fix netns vs. netlink table locking (2)

From: Johannes Berg <johannes@...solutions.net>
Date: Wed, 23 Sep 2009 11:34:30 +0200

> Similar to commit d136f1bd366fdb7e747ca7e0218171e7a00a98a5,
> there's a bug when unregistering a generic netlink family,
> which is caught by the might_sleep() added in that commit:
> 
>     BUG: sleeping function called from invalid context at net/netlink/af_netlink.c:183
>     in_atomic(): 1, irqs_disabled(): 0, pid: 1510, name: rmmod
>     2 locks held by rmmod/1510:
>      #0:  (genl_mutex){+.+.+.}, at: [<ffffffff8138283b>] genl_unregister_family+0x2b/0x130
>      #1:  (rcu_read_lock){.+.+..}, at: [<ffffffff8138270c>] __genl_unregister_mc_group+0x1c/0x120
>     Pid: 1510, comm: rmmod Not tainted 2.6.31-wl #444
>     Call Trace:
>      [<ffffffff81044ff9>] __might_sleep+0x119/0x150
>      [<ffffffff81380501>] netlink_table_grab+0x21/0x100
>      [<ffffffff813813a3>] netlink_clear_multicast_users+0x23/0x60
>      [<ffffffff81382761>] __genl_unregister_mc_group+0x71/0x120
>      [<ffffffff81382866>] genl_unregister_family+0x56/0x130
>      [<ffffffffa0007d85>] nl80211_exit+0x15/0x20 [cfg80211]
>      [<ffffffffa000005a>] cfg80211_exit+0x1a/0x40 [cfg80211]
> 
> Fix in the same way by grabbing the netlink table lock
> before doing rcu_read_lock().
> 
> Signed-off-by: Johannes Berg <johannes@...solutions.net>

Applied.
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