diff options
| author | Derek Foreman <derekf@osg.samsung.com> | 2016-11-24 19:11:55 +0100 |
|---|---|---|
| committer | Eric Anholt <eric@anholt.net> | 2016-11-30 00:39:45 +0100 |
| commit | 26fc78f6fef39b9d7a15def5e7e9826ff68303f4 (patch) | |
| tree | 7110f99026dbefcdb82ac1b46a71acd6714bfa37 /drivers/gpu | |
| parent | drm/vc4: Add fragment shader threading support (diff) | |
| download | linux-26fc78f6fef39b9d7a15def5e7e9826ff68303f4.tar.xz linux-26fc78f6fef39b9d7a15def5e7e9826ff68303f4.zip | |
drm/vc4: Fix race between page flip completion event and clean-up
There was a small window where a userspace program could submit
a pageflip after receiving a pageflip completion event yet still
receive EBUSY.
Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_crtc.c | 8 | ||||
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_drv.h | 1 | ||||
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_kms.c | 33 |
3 files changed, 34 insertions, 8 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c index 7f08d681a74b..82f914af4156 100644 --- a/drivers/gpu/drm/vc4/vc4_crtc.c +++ b/drivers/gpu/drm/vc4/vc4_crtc.c @@ -669,6 +669,14 @@ void vc4_disable_vblank(struct drm_device *dev, unsigned int crtc_id) CRTC_WRITE(PV_INTEN, 0); } +/* Must be called with the event lock held */ +bool vc4_event_pending(struct drm_crtc *crtc) +{ + struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc); + + return !!vc4_crtc->event; +} + static void vc4_crtc_handle_page_flip(struct vc4_crtc *vc4_crtc) { struct drm_crtc *crtc = &vc4_crtc->base; diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h index fef172804345..b3064e2e79c1 100644 --- a/drivers/gpu/drm/vc4/vc4_drv.h +++ b/drivers/gpu/drm/vc4/vc4_drv.h @@ -442,6 +442,7 @@ int vc4_bo_stats_debugfs(struct seq_file *m, void *arg); extern struct platform_driver vc4_crtc_driver; int vc4_enable_vblank(struct drm_device *dev, unsigned int crtc_id); void vc4_disable_vblank(struct drm_device *dev, unsigned int crtc_id); +bool vc4_event_pending(struct drm_crtc *crtc); int vc4_crtc_debugfs_regs(struct seq_file *m, void *arg); int vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id, unsigned int flags, int *vpos, int *hpos, diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c index c1f65c6c8e60..67af2af70af0 100644 --- a/drivers/gpu/drm/vc4/vc4_kms.c +++ b/drivers/gpu/drm/vc4/vc4_kms.c @@ -119,17 +119,34 @@ static int vc4_atomic_commit(struct drm_device *dev, /* Make sure that any outstanding modesets have finished. */ if (nonblock) { - ret = down_trylock(&vc4->async_modeset); - if (ret) { + struct drm_crtc *crtc; + struct drm_crtc_state *crtc_state; + unsigned long flags; + bool busy = false; + + /* + * If there's an undispatched event to send then we're + * obviously still busy. If there isn't, then we can + * unconditionally wait for the semaphore because it + * shouldn't be contended (for long). + * + * This is to prevent a race where queuing a new flip + * from userspace immediately on receipt of an event + * beats our clean-up and returns EBUSY. + */ + spin_lock_irqsave(&dev->event_lock, flags); + for_each_crtc_in_state(state, crtc, crtc_state, i) + busy |= vc4_event_pending(crtc); + spin_unlock_irqrestore(&dev->event_lock, flags); + if (busy) { kfree(c); return -EBUSY; } - } else { - ret = down_interruptible(&vc4->async_modeset); - if (ret) { - kfree(c); - return ret; - } + } + ret = down_interruptible(&vc4->async_modeset); + if (ret) { + kfree(c); + return ret; } ret = drm_atomic_helper_prepare_planes(dev, state); |