From 3bff93d64cf59f0e4547d5893adccc3925a14380 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sun, 22 Feb 2015 15:11:19 +0100 Subject: [PATCH] drm/irq: Don't call ->get_vblank_counter directly from irq_uninstall/cleanup The pipe might already have been shut down, and then it's not a good idea to call hw accessor functions. Instead use the same logic as drm_vblank_off which has all the necessary checks to avoid troubles or inconsistency. Noticed by Imre while reviewing my patches to remove some sanity checks from ->get_vblank_counter. v2: Try harder. disable_and_save can still access the vblank stuff when vblank->enabled isn't set. It has to, since vlbank irq could be disable but the pipe is still on when being called from drm_vblank_off. But we still want to use that code for more code sharing. So add a check for vblank->enabled on top - if that's not set we shouldn't have anyone waiting for the vblank. If we have that's a pretty serious bug. The other issue that Imre spotted is drm_vblank_cleanup. That code again calls disable_and_save and so suffers from the same issues. But really drm_irq_uninstall should have cleaned that all up, so replace the code with WARN_ON. Note that we can't delete the timer cleanup since drivers aren't required to use drm_irq_install/uninstall, but can do their own irq handling. v3: Make it clear that all that gunk in drm_irq_uninstall is really just bandaids for UMS races between the irq/vblank code. In UMS userspace is in control of enabling/disabling interrupts in general and vblanks specifically. v4: Imre observed that KMS drivers all call drm_vblank_cleanup before drm_irq_uninstall (as they should), so again the code in there is dead for KMS (due to dev->num_crtcs == 0 after drm_vblank_cleanup). Or should be, so only WARN for KMS - with UMS userspace could try to do evil things. v5: After more discussion on irc we've gone back to v3: the del_timer_sync is required in all cases in drm_vblank_cleanup, but let's restrict the WARN_ON to kms drivers only. Imre was also concerned that bad things could happen without the disable_and_save call. But we immediately free vblank structures afterwards which makes the save useless. And drm_handle_vblank has a check for dev->num_crtcs to avoid surprises with ums. Cc: Imre Deak Reviewed-by: Imre Deak Acked-by: Dave Airlie Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_irq.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index e78a1f5cad9c..4bb7d34ff79e 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -269,7 +269,6 @@ static void vblank_disable_fn(unsigned long arg) void drm_vblank_cleanup(struct drm_device *dev) { int crtc; - unsigned long irqflags; /* Bail if the driver didn't call drm_vblank_init() */ if (dev->num_crtcs == 0) @@ -278,11 +277,10 @@ void drm_vblank_cleanup(struct drm_device *dev) for (crtc = 0; crtc < dev->num_crtcs; crtc++) { struct drm_vblank_crtc *vblank = &dev->vblank[crtc]; - del_timer_sync(&vblank->disable_timer); + WARN_ON(vblank->enabled && + drm_core_check_feature(dev, DRIVER_MODESET)); - spin_lock_irqsave(&dev->vbl_lock, irqflags); - vblank_disable_and_save(dev, crtc); - spin_unlock_irqrestore(&dev->vbl_lock, irqflags); + del_timer_sync(&vblank->disable_timer); } kfree(dev->vblank); @@ -468,17 +466,23 @@ int drm_irq_uninstall(struct drm_device *dev) dev->irq_enabled = false; /* - * Wake up any waiters so they don't hang. + * Wake up any waiters so they don't hang. This is just to paper over + * isssues for UMS drivers which aren't in full control of their + * vblank/irq handling. KMS drivers must ensure that vblanks are all + * disabled when uninstalling the irq handler. */ if (dev->num_crtcs) { spin_lock_irqsave(&dev->vbl_lock, irqflags); for (i = 0; i < dev->num_crtcs; i++) { struct drm_vblank_crtc *vblank = &dev->vblank[i]; + if (!vblank->enabled) + continue; + + WARN_ON(drm_core_check_feature(dev, DRIVER_MODESET)); + + vblank_disable_and_save(dev, i); wake_up(&vblank->queue); - vblank->enabled = false; - vblank->last = - dev->driver->get_vblank_counter(dev, i); } spin_unlock_irqrestore(&dev->vbl_lock, irqflags); } -- 2.20.1