From ee3c7795e54f405fbd278b17d2e0cd8ca1c92b69 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sun, 22 Feb 2015 15:11:20 +0100 Subject: [PATCH] drm: WARN if drm_handle_vblank is called errornously KMS drivers are in full control of their irq and vblank handling, if they get a vblank interrupt before drm_vblank_init or after drm_vblank_cleanup that's just a driver bug. For ums driver there's only r128 and radeon which support vblank, and they call drm_vblank_init in their driver load functions. Which again means that userspace can do whatever it wants with interrupt, vblank structures will always be there. So this should never happen, let's catch driver issues with a WARN_ON. Motivated by some discussions with Imre. v2: Use WARN_ON_ONCE as suggested by Imre. Cc: Imre Deak Reviewed-by: Imre Deak Acked-by: Dave Airlie Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_irq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 4bb7d34ff79e..65a45ce70e2a 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -1682,7 +1682,7 @@ bool drm_handle_vblank(struct drm_device *dev, int crtc) struct timeval tvblank; unsigned long irqflags; - if (!dev->num_crtcs) + if (WARN_ON_ONCE(!dev->num_crtcs)) return false; if (WARN_ON(crtc >= dev->num_crtcs)) -- 2.20.1