Messages in this thread | | | Subject | Re: orinoco driver causes *lots* of lockdep spew | From | Arjan van de Ven <> | Date | Thu, 03 Aug 2006 14:15:59 +0200 |
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On Wed, 2006-08-02 at 17:59 -0400, Dave Jones wrote: > Wow. Nearly 400 lines of debug spew, from a simple 'ifup eth1'. > > Dave > > > ADDRCONF(NETDEV_UP): eth1: link is not ready > eth1: New link status: Disconnected (0002) > > ====================================================== > [ INFO: hard-safe -> hard-unsafe lock order detected ] > ------------------------------------------------------ > events/0/5 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: > (af_callback_keys + sk->sk_family){-.--}, at: [<ffffffff802136b1>] sock_def_readable+0x19/0x6f > > and this task is already holding: > (&priv->lock){++..}, at: [<ffffffff8824f70e>] orinoco_send_wevents+0x28/0x8b [orinoco] > which would create a new lock dependency: > (&priv->lock){++..} -> (af_callback_keys + sk->sk_family){-.--}
> [<ffffffff80267948>] _read_lock+0x28/0x34 > [<ffffffff802136b1>] sock_def_readable+0x19/0x6f > [<ffffffff80259ad7>] netlink_broadcast+0x222/0x2e2 > [<ffffffff804287eb>] wireless_send_event+0x300/0x317 > [<ffffffff8824f732>] :orinoco:orinoco_send_wevents+0x4c/0x8b > [<ffffffff8024f99c>] run_workqueue+0xa8/0xfb > [<ffffffff8024c180>] worker_thread+0xef/0x122 > [<ffffffff80235437>] kthread+0x100/0x136 > [<ffffffff802613de>] child_rip+0x8/0x12
this is another one of those nasty buggers;
Lock A = the sk->sk_callback_lock Lock B = priv->lock in the driver
Lock A is only BH safe Lock B is hardirq safe and used in the hardirq
Cpu 0 cpu 1 user closes the netlink socket takes lock B in orinoco_send_events takes lock A in user context in netlink_release() (for write) interrupt happens takes lock B in hardirq handler (spins)
calls netlink_broadcast which takes lock A for read (spins)
and you have a nice classical AB-BA deadlock
-- if you want to mail me at work (you don't), use arjan (at) linux.intel.com
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