From d53dab3ae1a3c6b438738c3792c98ac63f0061f4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 23 Jul 2011 12:45:07 +0200 Subject: [PATCH] drm: Remove utterly bogus preempt_disable() sections commit 27641c3f (drm/vblank: Add support for precise vblank timestamping) adds preempt_disable()/enable() around a spin locked section with the comments: * Disable preemption, so vblank_time_lock is held as short as * possible, even under a kernel with PREEMPT_RT patches. /* Disable preemption while holding vblank_time_lock. Do * it explicitely to guard against PREEMPT_RT kernel. Just that this has never been tested on a RT kernel which would have granted that nonsense with a might_sleep() warning because dev->vblank_time_lock is converted to a "sleeping" spinlock on RT. So this is activly wrong on RT and superflous on mainline. Remove it. Signed-off-by: Thomas Gleixner Acked-by: Mario Kleiner Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_irq.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 68b756253f9f..44a5d0ad8b7c 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -110,10 +110,7 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc) /* Prevent vblank irq processing while disabling vblank irqs, * so no updates of timestamps or count can happen after we've * disabled. Needed to prevent races in case of delayed irq's. - * Disable preemption, so vblank_time_lock is held as short as - * possible, even under a kernel with PREEMPT_RT patches. */ - preempt_disable(); spin_lock_irqsave(&dev->vblank_time_lock, irqflags); dev->driver->disable_vblank(dev, crtc); @@ -164,7 +161,6 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc) clear_vblank_timestamps(dev, crtc); spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags); - preempt_enable(); } static void vblank_disable_fn(unsigned long arg) @@ -889,10 +885,6 @@ int drm_vblank_get(struct drm_device *dev, int crtc) spin_lock_irqsave(&dev->vbl_lock, irqflags); /* Going from 0->1 means we have to enable interrupts again */ if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) { - /* Disable preemption while holding vblank_time_lock. Do - * it explicitely to guard against PREEMPT_RT kernel. - */ - preempt_disable(); spin_lock_irqsave(&dev->vblank_time_lock, irqflags2); if (!dev->vblank_enabled[crtc]) { /* Enable vblank irqs under vblank_time_lock protection. @@ -912,7 +904,6 @@ int drm_vblank_get(struct drm_device *dev, int crtc) } } spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags2); - preempt_enable(); } else { if (!dev->vblank_enabled[crtc]) { atomic_dec(&dev->vblank_refcount[crtc]); -- 2.20.1