| Message ID | 20180903211743.GA2773@haneenDRM (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/vkms: Fix race condition around accessing frame number | expand |
On Tue, Sep 04, 2018 at 12:18:17AM +0300, Haneen Mohammed wrote: > crtc_state is accessed by both vblank_handle() and the ordered > work_struct handle vkms_crc_work_handle() to retrieve and or update > the frame number for computed CRC. > > Since work_struct can fail, add frame_end to account for missing frame > numbers. > > Use (frame_[start/end]) for synchronization between hrtimer callback > and ordered work_struct handle. > > This patch passes the following subtests from igt kms_pipe_crc_basic test: > bad-source, read-crc-pipe-A, read-crc-pipe-A-frame-sequence, > nonblocking-crc-pipe-A, nonblocking-crc-pipe-A-frame-sequence > > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com> > --- > v2: > - use u64 with spinlock instead of atomic_t > - add out label for common exit routine @vkms_crc_work_handle() Yup I think that looks good, thanks for your patch. Applied. btw, do you still plan to type up a vkms.rst for documentation, so that we could put a few of the todo items there? Or should I do that? Next outreachy round starts soon, we need to get this ready. -Daniel > > drivers/gpu/drm/vkms/vkms_crc.c | 36 ++++++++++++++++++++++++++++++-- > drivers/gpu/drm/vkms/vkms_crtc.c | 16 ++++++++++++-- > drivers/gpu/drm/vkms/vkms_drv.h | 8 +++++-- > 3 files changed, 54 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c > index ed47d67cecd6..68db42f15086 100644 > --- a/drivers/gpu/drm/vkms/vkms_crc.c > +++ b/drivers/gpu/drm/vkms/vkms_crc.c > @@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data) > return crc; > } > > +/** > + * vkms_crc_work_handle - ordered work_struct to compute CRC > + * > + * @work: work_struct > + * > + * Work handler for computing CRCs. work_struct scheduled in > + * an ordered workqueue that's periodically scheduled to run by > + * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state(). > + */ > void vkms_crc_work_handle(struct work_struct *work) > { > struct vkms_crtc_state *crtc_state = container_of(work, > @@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work) > output); > struct vkms_crc_data *primary_crc = NULL; > struct drm_plane *plane; > - > u32 crc32 = 0; > + u64 frame_start, frame_end; > + unsigned long flags; > + > + spin_lock_irqsave(&out->state_lock, flags); > + frame_start = crtc_state->frame_start; > + frame_end = crtc_state->frame_end; > + spin_unlock_irqrestore(&out->state_lock, flags); > + > + /* _vblank_handle() hasn't updated frame_start yet */ > + if (!frame_start || frame_start == frame_end) > + goto out; > > drm_for_each_plane(plane, &vdev->drm) { > struct vkms_plane_state *vplane_state; > @@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work) > if (primary_crc) > crc32 = _vkms_get_crc(primary_crc); > > - drm_crtc_add_crc_entry(crtc, true, crtc_state->n_frame, &crc32); > + frame_end = drm_crtc_accurate_vblank_count(crtc); > + > + /* queue_work can fail to schedule crc_work; add crc for > + * missing frames > + */ > + while (frame_start <= frame_end) > + drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); > + > +out: > + /* to avoid using the same value for frame number again */ > + spin_lock_irqsave(&out->state_lock, flags); > + crtc_state->frame_end = frame_end; > + crtc_state->frame_start = 0; > + spin_unlock_irqrestore(&out->state_lock, flags); > } > > static int vkms_crc_parse_source(const char *src_name, bool *enabled) > diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c > index 9d0b1a325a78..177bbcb38306 100644 > --- a/drivers/gpu/drm/vkms/vkms_crtc.c > +++ b/drivers/gpu/drm/vkms/vkms_crtc.c > @@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output) > DRM_ERROR("vkms failure on handling vblank"); > > if (state && output->crc_enabled) { > - state->n_frame = drm_crtc_accurate_vblank_count(crtc); > - queue_work(output->crc_workq, &state->crc_work); > + u64 frame = drm_crtc_accurate_vblank_count(crtc); > + > + /* update frame_start only if a queued vkms_crc_work_handle() > + * has read the data > + */ > + spin_lock(&output->state_lock); > + if (!state->frame_start) > + state->frame_start = frame; > + spin_unlock(&output->state_lock); > + > + ret = queue_work(output->crc_workq, &state->crc_work); > + if (!ret) > + DRM_WARN("failed to queue vkms_crc_work_handle"); > } > > spin_unlock(&output->lock); > @@ -211,6 +222,7 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, > drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs); > > spin_lock_init(&vkms_out->lock); > + spin_lock_init(&vkms_out->state_lock); > > vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0); > > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h > index 2017a2ccc43d..80af6d3a65e7 100644 > --- a/drivers/gpu/drm/vkms/vkms_drv.h > +++ b/drivers/gpu/drm/vkms/vkms_drv.h > @@ -39,12 +39,14 @@ struct vkms_plane_state { > * vkms_crtc_state - Driver specific CRTC state > * @base: base CRTC state > * @crc_work: work struct to compute and add CRC entries > - * @n_frame: frame number for computed CRC > + * @n_frame_start: start frame number for computed CRC > + * @n_frame_end: end frame number for computed CRC > */ > struct vkms_crtc_state { > struct drm_crtc_state base; > struct work_struct crc_work; > - unsigned int n_frame; > + u64 frame_start; > + u64 frame_end; > }; > > struct vkms_output { > @@ -59,6 +61,8 @@ struct vkms_output { > struct workqueue_struct *crc_workq; > /* protects concurrent access to crc_data */ > spinlock_t lock; > + /* protects concurrent access to crtc_state */ > + spinlock_t state_lock; > }; > > struct vkms_device { > -- > 2.17.1 >
On Wed, Sep 05, 2018 at 04:03:26PM +0200, Daniel Vetter wrote: > On Tue, Sep 04, 2018 at 12:18:17AM +0300, Haneen Mohammed wrote: > > crtc_state is accessed by both vblank_handle() and the ordered > > work_struct handle vkms_crc_work_handle() to retrieve and or update > > the frame number for computed CRC. > > > > Since work_struct can fail, add frame_end to account for missing frame > > numbers. > > > > Use (frame_[start/end]) for synchronization between hrtimer callback > > and ordered work_struct handle. > > > > This patch passes the following subtests from igt kms_pipe_crc_basic test: > > bad-source, read-crc-pipe-A, read-crc-pipe-A-frame-sequence, > > nonblocking-crc-pipe-A, nonblocking-crc-pipe-A-frame-sequence > > > > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com> > > --- > > v2: > > - use u64 with spinlock instead of atomic_t > > - add out label for common exit routine @vkms_crc_work_handle() > > Yup I think that looks good, thanks for your patch. Applied. > > btw, do you still plan to type up a vkms.rst for documentation, so that we > could put a few of the todo items there? Or should I do that? Next > outreachy round starts soon, we need to get this ready. > -Daniel > I did prepare a patch for vkms.rst but since most of the todos I've so far are related to the cursor patch, I planed to send it after I submit the cursor patch. I'll send both out by the end of today. > > > > drivers/gpu/drm/vkms/vkms_crc.c | 36 ++++++++++++++++++++++++++++++-- > > drivers/gpu/drm/vkms/vkms_crtc.c | 16 ++++++++++++-- > > drivers/gpu/drm/vkms/vkms_drv.h | 8 +++++-- > > 3 files changed, 54 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c > > index ed47d67cecd6..68db42f15086 100644 > > --- a/drivers/gpu/drm/vkms/vkms_crc.c > > +++ b/drivers/gpu/drm/vkms/vkms_crc.c > > @@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data) > > return crc; > > } > > > > +/** > > + * vkms_crc_work_handle - ordered work_struct to compute CRC > > + * > > + * @work: work_struct > > + * > > + * Work handler for computing CRCs. work_struct scheduled in > > + * an ordered workqueue that's periodically scheduled to run by > > + * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state(). > > + */ > > void vkms_crc_work_handle(struct work_struct *work) > > { > > struct vkms_crtc_state *crtc_state = container_of(work, > > @@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work) > > output); > > struct vkms_crc_data *primary_crc = NULL; > > struct drm_plane *plane; > > - > > u32 crc32 = 0; > > + u64 frame_start, frame_end; > > + unsigned long flags; > > + > > + spin_lock_irqsave(&out->state_lock, flags); > > + frame_start = crtc_state->frame_start; > > + frame_end = crtc_state->frame_end; > > + spin_unlock_irqrestore(&out->state_lock, flags); > > + > > + /* _vblank_handle() hasn't updated frame_start yet */ > > + if (!frame_start || frame_start == frame_end) > > + goto out; > > > > drm_for_each_plane(plane, &vdev->drm) { > > struct vkms_plane_state *vplane_state; > > @@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work) > > if (primary_crc) > > crc32 = _vkms_get_crc(primary_crc); > > > > - drm_crtc_add_crc_entry(crtc, true, crtc_state->n_frame, &crc32); > > + frame_end = drm_crtc_accurate_vblank_count(crtc); > > + > > + /* queue_work can fail to schedule crc_work; add crc for > > + * missing frames > > + */ > > + while (frame_start <= frame_end) > > + drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); > > + > > +out: > > + /* to avoid using the same value for frame number again */ > > + spin_lock_irqsave(&out->state_lock, flags); > > + crtc_state->frame_end = frame_end; > > + crtc_state->frame_start = 0; > > + spin_unlock_irqrestore(&out->state_lock, flags); > > } > > > > static int vkms_crc_parse_source(const char *src_name, bool *enabled) > > diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c > > index 9d0b1a325a78..177bbcb38306 100644 > > --- a/drivers/gpu/drm/vkms/vkms_crtc.c > > +++ b/drivers/gpu/drm/vkms/vkms_crtc.c > > @@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output) > > DRM_ERROR("vkms failure on handling vblank"); > > > > if (state && output->crc_enabled) { > > - state->n_frame = drm_crtc_accurate_vblank_count(crtc); > > - queue_work(output->crc_workq, &state->crc_work); > > + u64 frame = drm_crtc_accurate_vblank_count(crtc); > > + > > + /* update frame_start only if a queued vkms_crc_work_handle() > > + * has read the data > > + */ > > + spin_lock(&output->state_lock); > > + if (!state->frame_start) > > + state->frame_start = frame; > > + spin_unlock(&output->state_lock); > > + > > + ret = queue_work(output->crc_workq, &state->crc_work); > > + if (!ret) > > + DRM_WARN("failed to queue vkms_crc_work_handle"); > > } > > > > spin_unlock(&output->lock); > > @@ -211,6 +222,7 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, > > drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs); > > > > spin_lock_init(&vkms_out->lock); > > + spin_lock_init(&vkms_out->state_lock); > > > > vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0); > > > > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h > > index 2017a2ccc43d..80af6d3a65e7 100644 > > --- a/drivers/gpu/drm/vkms/vkms_drv.h > > +++ b/drivers/gpu/drm/vkms/vkms_drv.h > > @@ -39,12 +39,14 @@ struct vkms_plane_state { > > * vkms_crtc_state - Driver specific CRTC state > > * @base: base CRTC state > > * @crc_work: work struct to compute and add CRC entries > > - * @n_frame: frame number for computed CRC > > + * @n_frame_start: start frame number for computed CRC > > + * @n_frame_end: end frame number for computed CRC > > */ > > struct vkms_crtc_state { > > struct drm_crtc_state base; > > struct work_struct crc_work; > > - unsigned int n_frame; > > + u64 frame_start; > > + u64 frame_end; > > }; > > > > struct vkms_output { > > @@ -59,6 +61,8 @@ struct vkms_output { > > struct workqueue_struct *crc_workq; > > /* protects concurrent access to crc_data */ > > spinlock_t lock; > > + /* protects concurrent access to crtc_state */ > > + spinlock_t state_lock; > > }; > > > > struct vkms_device { > > -- > > 2.17.1 > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c index ed47d67cecd6..68db42f15086 100644 --- a/drivers/gpu/drm/vkms/vkms_crc.c +++ b/drivers/gpu/drm/vkms/vkms_crc.c @@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data) return crc; } +/** + * vkms_crc_work_handle - ordered work_struct to compute CRC + * + * @work: work_struct + * + * Work handler for computing CRCs. work_struct scheduled in + * an ordered workqueue that's periodically scheduled to run by + * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state(). + */ void vkms_crc_work_handle(struct work_struct *work) { struct vkms_crtc_state *crtc_state = container_of(work, @@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work) output); struct vkms_crc_data *primary_crc = NULL; struct drm_plane *plane; - u32 crc32 = 0; + u64 frame_start, frame_end; + unsigned long flags; + + spin_lock_irqsave(&out->state_lock, flags); + frame_start = crtc_state->frame_start; + frame_end = crtc_state->frame_end; + spin_unlock_irqrestore(&out->state_lock, flags); + + /* _vblank_handle() hasn't updated frame_start yet */ + if (!frame_start || frame_start == frame_end) + goto out; drm_for_each_plane(plane, &vdev->drm) { struct vkms_plane_state *vplane_state; @@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work) if (primary_crc) crc32 = _vkms_get_crc(primary_crc); - drm_crtc_add_crc_entry(crtc, true, crtc_state->n_frame, &crc32); + frame_end = drm_crtc_accurate_vblank_count(crtc); + + /* queue_work can fail to schedule crc_work; add crc for + * missing frames + */ + while (frame_start <= frame_end) + drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); + +out: + /* to avoid using the same value for frame number again */ + spin_lock_irqsave(&out->state_lock, flags); + crtc_state->frame_end = frame_end; + crtc_state->frame_start = 0; + spin_unlock_irqrestore(&out->state_lock, flags); } static int vkms_crc_parse_source(const char *src_name, bool *enabled) diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 9d0b1a325a78..177bbcb38306 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output) DRM_ERROR("vkms failure on handling vblank"); if (state && output->crc_enabled) { - state->n_frame = drm_crtc_accurate_vblank_count(crtc); - queue_work(output->crc_workq, &state->crc_work); + u64 frame = drm_crtc_accurate_vblank_count(crtc); + + /* update frame_start only if a queued vkms_crc_work_handle() + * has read the data + */ + spin_lock(&output->state_lock); + if (!state->frame_start) + state->frame_start = frame; + spin_unlock(&output->state_lock); + + ret = queue_work(output->crc_workq, &state->crc_work); + if (!ret) + DRM_WARN("failed to queue vkms_crc_work_handle"); } spin_unlock(&output->lock); @@ -211,6 +222,7 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs); spin_lock_init(&vkms_out->lock); + spin_lock_init(&vkms_out->state_lock); vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0); diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h index 2017a2ccc43d..80af6d3a65e7 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -39,12 +39,14 @@ struct vkms_plane_state { * vkms_crtc_state - Driver specific CRTC state * @base: base CRTC state * @crc_work: work struct to compute and add CRC entries - * @n_frame: frame number for computed CRC + * @n_frame_start: start frame number for computed CRC + * @n_frame_end: end frame number for computed CRC */ struct vkms_crtc_state { struct drm_crtc_state base; struct work_struct crc_work; - unsigned int n_frame; + u64 frame_start; + u64 frame_end; }; struct vkms_output { @@ -59,6 +61,8 @@ struct vkms_output { struct workqueue_struct *crc_workq; /* protects concurrent access to crc_data */ spinlock_t lock; + /* protects concurrent access to crtc_state */ + spinlock_t state_lock; }; struct vkms_device {
crtc_state is accessed by both vblank_handle() and the ordered work_struct handle vkms_crc_work_handle() to retrieve and or update the frame number for computed CRC. Since work_struct can fail, add frame_end to account for missing frame numbers. Use (frame_[start/end]) for synchronization between hrtimer callback and ordered work_struct handle. This patch passes the following subtests from igt kms_pipe_crc_basic test: bad-source, read-crc-pipe-A, read-crc-pipe-A-frame-sequence, nonblocking-crc-pipe-A, nonblocking-crc-pipe-A-frame-sequence Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com> --- v2: - use u64 with spinlock instead of atomic_t - add out label for common exit routine @vkms_crc_work_handle() drivers/gpu/drm/vkms/vkms_crc.c | 36 ++++++++++++++++++++++++++++++-- drivers/gpu/drm/vkms/vkms_crtc.c | 16 ++++++++++++-- drivers/gpu/drm/vkms/vkms_drv.h | 8 +++++-- 3 files changed, 54 insertions(+), 6 deletions(-)