Re: [PATCH 2/2] ks8851: Fix mutex deadlock in ks8851_net_stop()

From: David Miller
Date: Sat Apr 21 2012 - 15:34:52 EST

From: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Date: Wed, 18 Apr 2012 20:25:58 -0700

> There is a potential deadlock scenario when the ks8851 driver
> is removed. The interrupt handler schedules a workqueue which
> acquires a mutex that ks8851_net_stop() also acquires before
> flushing the workqueue. Previously lockdep wouldn't be able
> to find this problem but now that it has the support we can
> trigger this lockdep warning by rmmoding the driver after
> an ifconfig up.
> Fix the possible deadlock by disabling the interrupts in
> the chip and then release the lock across the workqueue
> flushing. The mutex is only there to proect the registers
> anyway so this should be ok.
> Cc: Ben Dooks <ben-linux@xxxxxxxxx>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>

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