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 <tglx@linutronix.de>
Acked-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
parent
a7c36fd8c5
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@ -110,10 +110,7 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc)
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/* Prevent vblank irq processing while disabling vblank irqs,
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/* Prevent vblank irq processing while disabling vblank irqs,
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* so no updates of timestamps or count can happen after we've
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* so no updates of timestamps or count can happen after we've
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* disabled. Needed to prevent races in case of delayed irq's.
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* disabled. Needed to prevent races in case of delayed irq's.
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* Disable preemption, so vblank_time_lock is held as short as
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* possible, even under a kernel with PREEMPT_RT patches.
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*/
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*/
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preempt_disable();
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spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
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spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
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dev->driver->disable_vblank(dev, crtc);
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dev->driver->disable_vblank(dev, crtc);
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@ -164,7 +161,6 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc)
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clear_vblank_timestamps(dev, crtc);
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clear_vblank_timestamps(dev, crtc);
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spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
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spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
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preempt_enable();
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}
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}
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static void vblank_disable_fn(unsigned long arg)
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static void vblank_disable_fn(unsigned long arg)
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@ -889,10 +885,6 @@ int drm_vblank_get(struct drm_device *dev, int crtc)
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spin_lock_irqsave(&dev->vbl_lock, irqflags);
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spin_lock_irqsave(&dev->vbl_lock, irqflags);
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/* Going from 0->1 means we have to enable interrupts again */
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/* Going from 0->1 means we have to enable interrupts again */
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if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {
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if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {
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/* Disable preemption while holding vblank_time_lock. Do
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* it explicitely to guard against PREEMPT_RT kernel.
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*/
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preempt_disable();
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spin_lock_irqsave(&dev->vblank_time_lock, irqflags2);
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spin_lock_irqsave(&dev->vblank_time_lock, irqflags2);
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if (!dev->vblank_enabled[crtc]) {
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if (!dev->vblank_enabled[crtc]) {
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/* Enable vblank irqs under vblank_time_lock protection.
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/* Enable vblank irqs under vblank_time_lock protection.
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@ -912,7 +904,6 @@ int drm_vblank_get(struct drm_device *dev, int crtc)
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}
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}
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}
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}
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spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags2);
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spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags2);
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preempt_enable();
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} else {
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} else {
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if (!dev->vblank_enabled[crtc]) {
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if (!dev->vblank_enabled[crtc]) {
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atomic_dec(&dev->vblank_refcount[crtc]);
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atomic_dec(&dev->vblank_refcount[crtc]);
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