Re: [PATCH] mv643xx_eth: Fix a possible deadlock upon ifdown

Am 04.01.2013 21:25, schrieb Lennert Buytenhek:

On Fri, Jan 04, 2013 at 03:07:02PM +0100, Lubomir Rintel wrote:

quoted

From: Lubomir Rintel <redacted>

=================================
[ INFO: inconsistent lock state ]
3.7.0-6.luboskovo.fc19.armv5tel.kirkwood #1 Tainted: G        W
---------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
NetworkManager/337 [HC0[0]:SC0[0]:HE1:SE1] takes:
  (_xmit_ETHER#2){+.?...}, at: [<bf07adfc>] txq_reclaim+0x54/0x264 [mv643xx_eth]

I get the same annoying warning when the MTU gets changed (through dhcp).

Maybe I'm not reading it right, but I doubt that this is an actual
deadlock or that the patch is needed.

txq_reclaim() indeed doesn't disable BHs, but that's because it's
always called in BH context.  Almost always -- the only exception is
txq_deinit(), called from ->ndo_stop(), but by that time we've
already napi_disable()'d and netif_carrier_off()'d and free_irq()'d.

Agreed. I've just read me through that too and don't think a deadlock is 
possible.

How to explain that to lockdep, though, I don't know.

The patch helps with that. ;)

Regards,

Alexander