2020-07-20 19:12:02

by Lyude Paul

Subject: [PATCH 4/5] drm/vblank: Use spin_(un)lock_irq() in drm_queue_vblank_event()

This one's easy - we're already calling kzalloc() in this function, so
we must already be guaranteed to have IRQs enabled when calling this.
So, use the plain _irq() variants of spin_(un)lock() to make this more
obvious.

Signed-off-by: Lyude Paul <[email protected]>
Cc: Daniel Vetter <[email protected]>
---
drivers/gpu/drm/drm_vblank.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 51f2e988205e7..64610070ba473 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -1611,7 +1611,6 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
struct drm_pending_vblank_event *e;
ktime_t now;
- unsigned long flags;
u64 seq;
int ret;

@@ -1633,7 +1632,7 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
e->event.vbl.crtc_id = crtc->base.id;
}

- spin_lock_irqsave(&dev->event_lock, flags);
+ spin_lock_irq(&dev->event_lock);

/*
* drm_crtc_vblank_off() might have been called after we called
@@ -1670,12 +1669,12 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
vblwait->reply.sequence = req_seq;
}

- spin_unlock_irqrestore(&dev->event_lock, flags);
+ spin_unlock_irq(&dev->event_lock);

return 0;

err_unlock:
- spin_unlock_irqrestore(&dev->event_lock, flags);
+ spin_unlock_irq(&dev->event_lock);
kfree(e);
err_put:
drm_vblank_put(dev, pipe);
--
2.26.2

2020-07-21 06:53:42

by Daniel Vetter

Subject: Re: [PATCH 4/5] drm/vblank: Use spin_(un)lock_irq() in drm_queue_vblank_event()

On Mon, Jul 20, 2020 at 03:07:35PM -0400, Lyude Paul wrote:
> This one's easy - we're already calling kzalloc() in this function, so

Nit: "kzalloc(GFP_KERNEL)", since kzalloc(GFP_ATOMIC) is perfectly fine in
interrupt context. With that clarified for the entire series:

Reviewed-by: Daniel Vetter <[email protected]>

> we must already be guaranteed to have IRQs enabled when calling this.
> So, use the plain _irq() variants of spin_(un)lock() to make this more
> obvious.
>
> Signed-off-by: Lyude Paul <[email protected]>
> Cc: Daniel Vetter <[email protected]>
> ---
> drivers/gpu/drm/drm_vblank.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 51f2e988205e7..64610070ba473 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -1611,7 +1611,6 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
> struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
> struct drm_pending_vblank_event *e;
> ktime_t now;
> - unsigned long flags;
> u64 seq;
> int ret;
>
> @@ -1633,7 +1632,7 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
> e->event.vbl.crtc_id = crtc->base.id;
> }
>
> - spin_lock_irqsave(&dev->event_lock, flags);
> + spin_lock_irq(&dev->event_lock);
>
> /*
> * drm_crtc_vblank_off() might have been called after we called
> @@ -1670,12 +1669,12 @@ static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
> vblwait->reply.sequence = req_seq;
> }
>
> - spin_unlock_irqrestore(&dev->event_lock, flags);
> + spin_unlock_irq(&dev->event_lock);
>
> return 0;
>
> err_unlock:
> - spin_unlock_irqrestore(&dev->event_lock, flags);
> + spin_unlock_irq(&dev->event_lock);
> kfree(e);
> err_put:
> drm_vblank_put(dev, pipe);
> --
> 2.26.2
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch