linux-kernel - Re: [PATCH 2/2] drm/nouveau: Check that the device is enabled before processing interrupt

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Date:	Wed, 4 May 2011 13:50:19 +1000
From:	Dave Airlie <airlied@...il.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	airlied@...ux.ie, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/nouveau: Check that the device is enabled before
 processing interrupt

On Mon, May 2, 2011 at 10:49 AM, Alex Williamson
<alex.williamson@...hat.com> wrote:
> We're likely to be sharing an interrupt line with other devices,
> which means our handler might get called after we've turned off
> the device via vga switcheroo.  This can lead to all sorts of
> badness, like nv04_fifo_isr() spewing "PFIFO still angry after
> 100 spins, halt" to the console before the system enters a hard
> hang.
>
> We can avoid this by simply checking if the device is still
> enabled before processing an interrupt.  To avoid races, flush
> any inflight interrupts using synchronize_irq().  Note that
> since pci_intx() is called after pci_save_state(),
> pci_restore_state() will automatically re-enable INTx.

I still think we should just need the synchronize_irq followed by a
check in the irq handler for all fs,

or is there a race there I'm missing?

Dave.
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