The dev->struct_mutex locking in drm_irq.c only protects dev->irq_enabled. Which isn't really much at all and only prevents especially nasty ums userspace from concurrently installing the interrupt handling a few times. Or at least trying.
There are tons of unlocked readers of dev->irqs_enabled in the vblank wait code (and by extension also in the pageflip code since that uses the same vblank timestamp engine).
Real modesetting drivers should ensure that nothing can go haywire with a sane setup teardown sequence. So we only really need this for the drm_control ioctl, everywhere else this will just paper over nastiness.
Note that drm/i915 is a bit specially due to the gem+ums combination. So there we also need to properly protect the entervt and leavevt ioctls. But it's definitely saner to do everything in one go than to drop the lock in-between.
Finally there's the gpu reset code in drm/i915. That one's just race (concurrent userspace calls to for vblank waits of pageflips could spuriously fail). So wrap it up in with a nice comment since fixing this is more involved.
Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_irq.c | 30 +++++++++++++----------------- drivers/gpu/drm/i915/i915_drv.c | 5 +++++ drivers/gpu/drm/i915/i915_gem.c | 5 +++-- 3 files changed, 21 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 3faf1e94df02..d24ac519c6f3 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -254,20 +254,13 @@ int drm_irq_install(struct drm_device *dev) if (drm_dev_to_irq(dev) == 0) return -EINVAL;
- mutex_lock(&dev->struct_mutex); - /* Driver must have been initialized */ - if (!dev->dev_private) { - mutex_unlock(&dev->struct_mutex); + if (!dev->dev_private) return -EINVAL; - }
- if (dev->irq_enabled) { - mutex_unlock(&dev->struct_mutex); + if (dev->irq_enabled) return -EBUSY; - } dev->irq_enabled = true; - mutex_unlock(&dev->struct_mutex);
DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
@@ -288,9 +281,7 @@ int drm_irq_install(struct drm_device *dev) sh_flags, irqname, dev);
if (ret < 0) { - mutex_lock(&dev->struct_mutex); dev->irq_enabled = false; - mutex_unlock(&dev->struct_mutex); return ret; }
@@ -302,9 +293,7 @@ int drm_irq_install(struct drm_device *dev) ret = dev->driver->irq_postinstall(dev);
if (ret < 0) { - mutex_lock(&dev->struct_mutex); dev->irq_enabled = false; - mutex_unlock(&dev->struct_mutex); if (!drm_core_check_feature(dev, DRIVER_MODESET)) vga_client_register(dev->pdev, NULL, NULL, NULL); free_irq(drm_dev_to_irq(dev), dev); @@ -330,10 +319,8 @@ int drm_irq_uninstall(struct drm_device *dev) if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ)) return -EINVAL;
- mutex_lock(&dev->struct_mutex); irq_enabled = dev->irq_enabled; dev->irq_enabled = false; - mutex_unlock(&dev->struct_mutex);
/* * Wake up any waiters so they don't hang. @@ -381,6 +368,7 @@ int drm_control(struct drm_device *dev, void *data, struct drm_file *file_priv) { struct drm_control *ctl = data; + int ret = 0;
/* if we haven't irq we fallback for compatibility reasons - * this used to be a separate function in drm_dma.h @@ -400,9 +388,17 @@ int drm_control(struct drm_device *dev, void *data, ctl->irq != drm_dev_to_irq(dev)) return -EINVAL;
- return drm_irq_install(dev); + mutex_lock(&dev->struct_mutex); + ret = drm_irq_install(dev); + mutex_unlock(&dev->struct_mutex); + + return ret; case DRM_UNINST_HANDLER: - return drm_irq_uninstall(dev); + mutex_lock(&dev->struct_mutex); + ret = drm_irq_uninstall(dev); + mutex_unlock(&dev->struct_mutex); + + return ret; default: return -EINVAL; } diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 06600ac18716..95541d1e5b43 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -799,6 +799,11 @@ int i915_reset(struct drm_device *dev) return ret; }
+ /* + * FIXME: This is horribly race against concurrent pageflip and + * vblank wait ioctls since they can observe dev->irqs_disabled + * being false when they shouldn't be able to. + */ drm_irq_uninstall(dev); drm_irq_install(dev); intel_hpd_init(dev); diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 12bbd5eac70d..b8c500bf56b7 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4543,16 +4543,15 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data, }
BUG_ON(!list_empty(&dev_priv->gtt.base.active_list)); - mutex_unlock(&dev->struct_mutex);
ret = drm_irq_install(dev); if (ret) goto cleanup_ringbuffer; + mutex_unlock(&dev->struct_mutex);
return 0;
cleanup_ringbuffer: - mutex_lock(&dev->struct_mutex); i915_gem_cleanup_ringbuffer(dev); dev_priv->ums.mm_suspended = 1; mutex_unlock(&dev->struct_mutex); @@ -4567,7 +4566,9 @@ i915_gem_leavevt_ioctl(struct drm_device *dev, void *data, if (drm_core_check_feature(dev, DRIVER_MODESET)) return 0;
+ mutex_lock(&dev->struct_mutex); drm_irq_uninstall(dev); + mutex_unlock(&dev->struct_mutex);
return i915_gem_suspend(dev); }