On Mon, Jun 30, 2014 at 5:12 AM, Michel Dänzer <michel@xxxxxxxxxxx> wrote:
> From: Michel Dänzer <michel.daenzer@xxxxxxx>
>
> This prevents a panic: radeon_crtc_handle_page_flip() could run before
> radeon_flip_work_func(), triggering the BUG_ON() in drm_vblank_put().
>
> Tested-by: Dieter Nützel <Dieter@xxxxxxxxxxxxx>
> Signed-off-by: Michel Dänzer <michel.daenzer@xxxxxxx>
> ---
>
> v2: Update log message
Applied to to by -fixes tree.
Alex
>
> drivers/gpu/drm/radeon/radeon_display.c | 19 ++++++++++++++-----
> drivers/gpu/drm/radeon/radeon_mode.h | 7 +++++++
> 2 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index 8b575a4..65882cd 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -284,7 +284,6 @@ static void radeon_unpin_work_func(struct work_struct *__work)
> void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
> {
> struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
> - struct radeon_flip_work *work;
> unsigned long flags;
> u32 update_pending;
> int vpos, hpos;
> @@ -294,8 +293,11 @@ void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
> return;
>
> spin_lock_irqsave(&rdev->ddev->event_lock, flags);
> - work = radeon_crtc->flip_work;
> - if (work == NULL) {
> + if (radeon_crtc->flip_status != RADEON_FLIP_SUBMITTED) {
> + DRM_DEBUG_DRIVER("radeon_crtc->flip_status = %d != "
> + "RADEON_FLIP_SUBMITTED(%d)\n",
> + radeon_crtc->flip_status,
> + RADEON_FLIP_SUBMITTED);
> spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
> return;
> }
> @@ -343,12 +345,17 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
>
> spin_lock_irqsave(&rdev->ddev->event_lock, flags);
> work = radeon_crtc->flip_work;
> - if (work == NULL) {
> + if (radeon_crtc->flip_status != RADEON_FLIP_SUBMITTED) {
> + DRM_DEBUG_DRIVER("radeon_crtc->flip_status = %d != "
> + "RADEON_FLIP_SUBMITTED(%d)\n",
> + radeon_crtc->flip_status,
> + RADEON_FLIP_SUBMITTED);
> spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
> return;
> }
>
> /* Pageflip completed. Clean up. */
> + radeon_crtc->flip_status = RADEON_FLIP_NONE;
> radeon_crtc->flip_work = NULL;
>
> /* wakeup userspace */
> @@ -475,6 +482,7 @@ static void radeon_flip_work_func(struct work_struct *__work)
> /* do the flip (mmio) */
> radeon_page_flip(rdev, radeon_crtc->crtc_id, base);
>
> + radeon_crtc->flip_status = RADEON_FLIP_SUBMITTED;
> spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> up_read(&rdev->exclusive_lock);
>
> @@ -543,7 +551,7 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
> /* We borrow the event spin lock for protecting flip_work */
> spin_lock_irqsave(&crtc->dev->event_lock, flags);
>
> - if (radeon_crtc->flip_work) {
> + if (radeon_crtc->flip_status != RADEON_FLIP_NONE) {
> DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
> spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> drm_gem_object_unreference_unlocked(&work->old_rbo->gem_base);
> @@ -551,6 +559,7 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
> kfree(work);
> return -EBUSY;
> }
> + radeon_crtc->flip_status = RADEON_FLIP_PENDING;
> radeon_crtc->flip_work = work;
>
> /* update crtc fb */
> diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
> index b59096f..ed6b6e0 100644
> --- a/drivers/gpu/drm/radeon/radeon_mode.h
> +++ b/drivers/gpu/drm/radeon/radeon_mode.h
> @@ -301,6 +301,12 @@ struct radeon_atom_ss {
> uint16_t amount;
> };
>
> +enum radeon_flip_status {
> + RADEON_FLIP_NONE,
> + RADEON_FLIP_PENDING,
> + RADEON_FLIP_SUBMITTED
> +};
> +
> struct radeon_crtc {
> struct drm_crtc base;
> int crtc_id;
> @@ -326,6 +332,7 @@ struct radeon_crtc {
> /* page flipping */
> struct workqueue_struct *flip_queue;
> struct radeon_flip_work *flip_work;
> + enum radeon_flip_status flip_status;
> /* pll sharing */
> struct radeon_atom_ss ss;
> bool ss_enabled;
> --
> 2.0.0
>
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