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

From: Daniel Vetter
Date: Tue Jul 21 2020 - 02:51:05 EST


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 <daniel.vetter@xxxxxxxx>

> 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 <lyude@xxxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> ---
> 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