bug: mutex_lock() in interrupt conntext via phy_stop() in gianfar

[Nate Case]

On Fri, 2008-07-18 at 14:10 +0200, Sebastian Siewior wrote:
> Commit 35b5f6b1a aka [PHYLIB: Locking fixes for PHY I/O potentially sleeping]
> changed the phydev->lock from spinlock into a mutex. Now, the following
> code path got triggered while NFS was unavailable:
> 
[snip]
> |[  194.864733] BUG: sleeping function called from invalid context at /home/bigeasy/git/linux-2.6-powerpc/kernel/mutex.c:87
> |[  194.875529] in_atomic():1, irqs_disabled():0
> |[  194.879805] Call Trace:
> |[  194.882250] [c0383d90] [c0006dd8] show_stack+0x48/0x184 (unreliable)
> |[  194.888649] [c0383db0] [c001e938] __might_sleep+0xe0/0xf4
> |[  194.894069] [c0383dc0] [c025a43c] mutex_lock+0x24/0x3c
> |[  194.899234] [c0383de0] [c019005c] phy_stop+0x20/0x70
> |[  194.904234] [c0383df0] [c018d4ec] stop_gfar+0x28/0xf4
> |[  194.909305] [c0383e10] [c018e8c4] gfar_timeout+0x30/0x60
> |[  194.914638] [c0383e20] [c01fe7c0] dev_watchdog+0xa8/0x144

Hmm..  I'm not sure what the best solution is to this.  Make the
stop_gfar() call happen in a workqueue, and make a similar change to
ucc_geth, fec_mpc52xx, and fs_enet? Modify phy_stop() to do the work in
a workqueue conditionally if in interrupt context?  Between these two
I'd lean toward the latter.

Does anyone have any better ideas?

-- 
Nate Case <ncase at xes-inc.com>