This is a follow-up series for finishing the work that we started here:
https://patchwork.freedesktop.org/patch/373107/?series=74805&rev=8
tl;dr many of the drm_vblank functions only get called within irq-enabled contexts, so we go through those and convert them over to using spin_(un)lock_irq() to make this fact more obvious in case we need to add more blocking calls to any of these functions in the future.
Lyude Paul (5): drm/vblank: Use spin_(un)lock_irq() in drm_crtc_vblank_reset() drm/vblank: Use spin_(un)lock_irq() in drm_crtc_vblank_on() drm/vblank: Use spin_(un)lock_irq() in drm_legacy_vblank_post_modeset() drm/vblank: Use spin_(un)lock_irq() in drm_queue_vblank_event() drm/vblank: Use spin_(un)lock_irq() in drm_crtc_queue_sequence_ioctl()
drivers/gpu/drm/drm_vblank.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-)
All of the drivers in the kernel tree only call this from one of the following contexts:
* drm_crtc_funcs->reset * During initial module load
Since both of these contexts are guaranteed to have interrupts enabled beforehand, there's no need to use the irqsave/irqrestore variants of spin_(un)lock(). So, fix this to make the irq context of this function more obvious.
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Daniel Vetter daniel@ffwll.ch --- drivers/gpu/drm/drm_vblank.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index f402c75b9d343..6af78aecea9d4 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1363,11 +1363,10 @@ EXPORT_SYMBOL(drm_crtc_vblank_off); void drm_crtc_vblank_reset(struct drm_crtc *crtc) { struct drm_device *dev = crtc->dev; - unsigned long irqflags; unsigned int pipe = drm_crtc_index(crtc); struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
- spin_lock_irqsave(&dev->vbl_lock, irqflags); + spin_lock_irq(&dev->vbl_lock); /* * Prevent subsequent drm_vblank_get() from enabling the vblank * interrupt by bumping the refcount. @@ -1376,7 +1375,7 @@ void drm_crtc_vblank_reset(struct drm_crtc *crtc) atomic_inc(&vblank->refcount); vblank->inmodeset = 1; } - spin_unlock_irqrestore(&dev->vbl_lock, irqflags); + spin_unlock_irq(&dev->vbl_lock);
drm_WARN_ON(dev, !list_empty(&dev->vblank_event_list)); drm_WARN_ON(dev, !list_empty(&vblank->pending_work));
This is only called from: * Atomic modesetting hooks * Module probing routines * Legacy modesetting hooks
All of which have IRQs enabled, so we can also get rid of irqsave/restore here to make the IRQ context of this function more obvious.
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Daniel Vetter daniel@ffwll.ch --- drivers/gpu/drm/drm_vblank.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 6af78aecea9d4..9891e82939e35 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1428,12 +1428,11 @@ void drm_crtc_vblank_on(struct drm_crtc *crtc) struct drm_device *dev = crtc->dev; unsigned int pipe = drm_crtc_index(crtc); struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; - unsigned long irqflags;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs)) return;
- spin_lock_irqsave(&dev->vbl_lock, irqflags); + spin_lock_irq(&dev->vbl_lock); drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n", pipe, vblank->enabled, vblank->inmodeset);
@@ -1451,7 +1450,7 @@ void drm_crtc_vblank_on(struct drm_crtc *crtc) */ if (atomic_read(&vblank->refcount) != 0 || drm_vblank_offdelay == 0) drm_WARN_ON(dev, drm_vblank_enable(dev, pipe)); - spin_unlock_irqrestore(&dev->vbl_lock, irqflags); + spin_unlock_irq(&dev->vbl_lock); } EXPORT_SYMBOL(drm_crtc_vblank_on);
This function is only ever called from ioctl context, so we're guaranteed to have interrupts enabled. Stop using the irqsave/irqrestore variants of spin_(un)lock_irq() to make this more obvious.
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Daniel Vetter daniel@ffwll.ch --- drivers/gpu/drm/drm_vblank.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 9891e82939e35..51f2e988205e7 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1551,7 +1551,6 @@ static void drm_legacy_vblank_post_modeset(struct drm_device *dev, unsigned int pipe) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; - unsigned long irqflags;
/* vblank is not initialized (IRQ not installed ?), or has been freed */ if (!drm_dev_has_vblank(dev)) @@ -1561,9 +1560,9 @@ static void drm_legacy_vblank_post_modeset(struct drm_device *dev, return;
if (vblank->inmodeset) { - spin_lock_irqsave(&dev->vbl_lock, irqflags); + spin_lock_irq(&dev->vbl_lock); drm_reset_vblank_timestamp(dev, pipe); - spin_unlock_irqrestore(&dev->vbl_lock, irqflags); + spin_unlock_irq(&dev->vbl_lock);
if (vblank->inmodeset & 0x2) drm_vblank_put(dev, pipe);
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 lyude@redhat.com Cc: Daniel Vetter daniel@ffwll.ch --- 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);
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@ffwll.ch
This is an ioctl callback, so we're guaranteed to have IRQs enabled when calling this function. Use the plain _irq() variants of spin_(un)lock() to make this more obvious.
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Daniel Vetter daniel@ffwll.ch --- 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 64610070ba473..b18e1efbbae1a 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -2066,7 +2066,6 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, u64 seq; u64 req_seq; int ret; - unsigned long spin_flags;
if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; @@ -2114,7 +2113,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, e->event.base.length = sizeof(e->event.seq); e->event.seq.user_data = queue_seq->user_data;
- spin_lock_irqsave(&dev->event_lock, spin_flags); + spin_lock_irq(&dev->event_lock);
/* * drm_crtc_vblank_off() might have been called after we called @@ -2145,11 +2144,11 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, queue_seq->sequence = req_seq; }
- spin_unlock_irqrestore(&dev->event_lock, spin_flags); + spin_unlock_irq(&dev->event_lock); return 0;
err_unlock: - spin_unlock_irqrestore(&dev->event_lock, spin_flags); + spin_unlock_irq(&dev->event_lock); drm_crtc_vblank_put(crtc); err_free: kfree(e);
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Lyude Paul