On Sun, May 27, 2012 at 10:25:21PM +0200, Marcin Slusarz wrote:
> On Thu, May 24, 2012 at 08:09:41PM +0200, Bruno Prémont wrote:
> > I can easily trigger a crash in nouveau interrupt handler by unbinding
> > and rebinding the GPU.
> >
> > The command used:
> > echo $pci_device > nouveau/unbind && \
> > sleep 5 && \
> > echo $pci_device > nouveau/bind
> >
> >
> > Kernel is 3.4.0 with modular drm/nouveau.
> > GPU is NVidia nForce IGP (NV11)
> >
> >
> > Unbinding seems to work fine, display switching back to VGA text mode.
> > Rebinding the GPU slightly later causes the below trace:
> >
> > (...)
>
> It crashed because Nouveau failed to disable vblank interrupt on unbind
> and this interrupt triggered while drm was initializing vblank data.
>
> Nouveau side was fixed by "drm/nv04/disp: disable vblank interrupts when
> disabling display" by Ben Skeggs (3.5 merge window), drm side can be fixed
> by this:
>
> ---
> From: Marcin Slusarz <marcin.slusarz@xxxxxxxxx>
> Subject: [PATCH] drm: do not expose vblank data before drm_vblank_init completes
>
> It fixes oops in drm_handle_vblank when vblank interrupt triggers before
> drm_vblank_init completes. Driver side should not let this happen, but let's
> be on the safe side and handle this case.
>
> Reported-by: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx>
> Tested-by: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Marcin Slusarz <marcin.slusarz@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_irq.c | 21 +++++++++++++--------
> 1 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index c869436..7dda18c 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -183,12 +183,8 @@ static void vblank_disable_fn(unsigned long arg)
> }
> }
>
> -void drm_vblank_cleanup(struct drm_device *dev)
> +static void __drm_vblank_cleanup(struct drm_device *dev)
> {
> - /* Bail if the driver didn't call drm_vblank_init() */
> - if (dev->num_crtcs == 0)
> - return;
> -
> del_timer(&dev->vblank_disable_timer);
>
> vblank_disable_fn((unsigned long)dev);
> @@ -201,6 +197,15 @@ void drm_vblank_cleanup(struct drm_device *dev)
> kfree(dev->last_vblank_wait);
> kfree(dev->vblank_inmodeset);
> kfree(dev->_vblank_time);
> +}
> +
> +void drm_vblank_cleanup(struct drm_device *dev)
> +{
> + /* Bail if the driver didn't call drm_vblank_init() */
> + if (dev->num_crtcs == 0)
> + return;
> +
> + __drm_vblank_cleanup(dev);
>
> dev->num_crtcs = 0;
> }
> @@ -215,8 +220,6 @@ int drm_vblank_init(struct drm_device *dev, int num_crtcs)
> spin_lock_init(&dev->vbl_lock);
> spin_lock_init(&dev->vblank_time_lock);
>
> - dev->num_crtcs = num_crtcs;
> -
> dev->vbl_queue = kmalloc(sizeof(wait_queue_head_t) * num_crtcs,
> GFP_KERNEL);
> if (!dev->vbl_queue)
> @@ -268,10 +271,12 @@ int drm_vblank_init(struct drm_device *dev, int num_crtcs)
> }
>
> dev->vblank_disable_allowed = 0;
> + dev->num_crtcs = num_crtcs;
> +
> return 0;
>
> err:
> - drm_vblank_cleanup(dev);
> + __drm_vblank_cleanup(dev);
> return ret;
> }
> EXPORT_SYMBOL(drm_vblank_init);
> --
Dave?
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