On Thu, 09 Apr 2015, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote:
> We must acquire the mutex before we can check drrs.dp, otherwise
> someone might sneak in with a modeset, clear the pointer after we've
> checked it and then the code will Oops.
>
> This issue has been introduced in
>
> commit a93fad0f7fb8a3ff12e8814b630648f6d187954c
> Author: Vandana Kannan <vandana.kannan@xxxxxxxxx>
> Date: Sat Jan 10 02:25:59 2015 +0530
>
> drm/i915: DRRS calls based on frontbuffer
>
> Cc: Ramalingam C <ramalingam.c@xxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Vandana Kannan <vandana.kannan@xxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Missed 4.0 so this is
Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/gpu/drm/i915/intel_dp.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 1b87969536ff..e265a0dee479 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5170,7 +5170,6 @@ static void intel_edp_drrs_downclock_work(struct work_struct *work)
> downclock_mode->vrefresh);
>
> unlock:
> -
> mutex_unlock(&dev_priv->drrs.mutex);
> }
>
> @@ -5192,12 +5191,14 @@ void intel_edp_drrs_invalidate(struct drm_device *dev,
> struct drm_crtc *crtc;
> enum pipe pipe;
>
> - if (!dev_priv->drrs.dp)
> - return;
> -
> cancel_delayed_work_sync(&dev_priv->drrs.work);
>
> mutex_lock(&dev_priv->drrs.mutex);
> + if (!dev_priv->drrs.dp) {
> + mutex_unlock(&dev_priv->drrs.mutex);
> + return;
> + }
> +
> crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc;
> pipe = to_intel_crtc(crtc)->pipe;
>
> @@ -5231,12 +5232,14 @@ void intel_edp_drrs_flush(struct drm_device *dev,
> struct drm_crtc *crtc;
> enum pipe pipe;
>
> - if (!dev_priv->drrs.dp)
> - return;
> -
> cancel_delayed_work_sync(&dev_priv->drrs.work);
>
> mutex_lock(&dev_priv->drrs.mutex);
> + if (!dev_priv->drrs.dp) {
> + mutex_unlock(&dev_priv->drrs.mutex);
> + return;
> + }
> +
> crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc;
> pipe = to_intel_crtc(crtc)->pipe;
> dev_priv->drrs.busy_frontbuffer_bits &= ~frontbuffer_bits;
> --
> 2.1.4
>
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
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--
Jani Nikula, Intel Open Source Technology Center
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