=======================================================
[ INFO: possible circular locking dependency detected ]
3.0.21-00021-g8b33780-dirty #2911
-------------------------------------------------------
rmmod/125 is trying to acquire lock:
((&ks->irq_work)){+.+...}, at: [<c019e0b8>] flush_work+0x0/0xac
but task is already holding lock:
(&ks->lock){+.+...}, at: [<bf00b850>] ks8851_net_stop+0x64/0x138 [ks8851]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&ks->lock){+.+...}:
[<c01b89c8>] __lock_acquire+0x940/0x9f8
[<c01b9058>] lock_acquire+0x10c/0x130
[<c083dbec>] mutex_lock_nested+0x68/0x3dc
[<bf00bd48>] ks8851_irq_work+0x24/0x46c [ks8851]
[<c019c580>] process_one_work+0x2d8/0x518
[<c019cb98>] worker_thread+0x220/0x3a0
[<c01a2ad4>] kthread+0x88/0x94
[<c0107008>] kernel_thread_exit+0x0/0x8
-> #0 ((&ks->irq_work)){+.+...}:
[<c01b7984>] validate_chain+0x914/0x1018
[<c01b89c8>] __lock_acquire+0x940/0x9f8
[<c01b9058>] lock_acquire+0x10c/0x130
[<c019e104>] flush_work+0x4c/0xac
[<bf00b858>] ks8851_net_stop+0x6c/0x138 [ks8851]
[<c06b209c>] __dev_close_many+0x98/0xcc
[<c06b2174>] dev_close_many+0x68/0xd0
[<c06b22ec>] rollback_registered_many+0xcc/0x2b8
[<c06b2554>] rollback_registered+0x28/0x34
[<c06b25b8>] unregister_netdevice_queue+0x58/0x7c
[<c06b25f4>] unregister_netdev+0x18/0x20
[<bf00c1f4>] ks8851_remove+0x64/0xb4 [ks8851]
[<c049ddf0>] spi_drv_remove+0x18/0x1c
[<c0468e98>] __device_release_driver+0x7c/0xbc
[<c0468f64>] driver_detach+0x8c/0xb4
[<c0467f00>] bus_remove_driver+0xb8/0xe8
[<c01c1d20>] sys_delete_module+0x1e8/0x27c
[<c0105ec0>] ret_fast_syscall+0x0/0x3c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&ks->lock);
lock((&ks->irq_work));
lock(&ks->lock);
lock((&ks->irq_work));
*** DEADLOCK ***
4 locks held by rmmod/125:
#0: (&__lockdep_no_validate__){+.+.+.}, at: [<c0468f44>] driver_detach+0x6c/0xb4
#1: (&__lockdep_no_validate__){+.+.+.}, at: [<c0468f50>] driver_detach+0x78/0xb4
#2: (rtnl_mutex){+.+.+.}, at: [<c06b25e8>] unregister_netdev+0xc/0x20
#3: (&ks->lock){+.+...}, at: [<bf00b850>] ks8851_net_stop+0x64/0x138 [ks8851]
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
drivers/net/ethernet/micrel/ks8851.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
@@ -889,16 +889,17 @@ static int ks8851_net_stop(struct net_device *dev)
netif_stop_queue(dev);
mutex_lock(&ks->lock);
+ /* turn off the IRQs and ack any outstanding */
+ ks8851_wrreg16(ks, KS_IER, 0x0000);
+ ks8851_wrreg16(ks, KS_ISR, 0xffff);
+ mutex_unlock(&ks->lock);
/* stop any outstanding work */
flush_work(&ks->irq_work);
flush_work(&ks->tx_work);
flush_work(&ks->rxctrl_work);
- /* turn off the IRQs and ack any outstanding */
- ks8851_wrreg16(ks, KS_IER, 0x0000);
- ks8851_wrreg16(ks, KS_ISR, 0xffff);
-
+ mutex_lock(&ks->lock);
/* shutdown RX process */
ks8851_wrreg16(ks, KS_RXCR1, 0x0000);
@@ -907,6 +908,7 @@ static int ks8851_net_stop(struct net_device *dev)
/* set powermode to soft power down to save power */
ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);
+ mutex_unlock(&ks->lock);
/* ensure any queued tx buffers are dumped */
while (!skb_queue_empty(&ks->txq)) {
@@ -918,7 +920,6 @@ static int ks8851_net_stop(struct net_device *dev)
dev_kfree_skb(txb);
}
- mutex_unlock(&ks->lock);
return 0;
}