Commit 0ca33adb authored by Haneen Mohammed's avatar Haneen Mohammed Committed by Daniel Vetter

drm/vkms: Fix race condition around accessing frame number

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: default avatarHaneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180903211743.GA2773@haneenDRM
parent 428e15cc
...@@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data) ...@@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data)
return crc; 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) void vkms_crc_work_handle(struct work_struct *work)
{ {
struct vkms_crtc_state *crtc_state = container_of(work, struct vkms_crtc_state *crtc_state = container_of(work,
...@@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work) ...@@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work)
output); output);
struct vkms_crc_data *primary_crc = NULL; struct vkms_crc_data *primary_crc = NULL;
struct drm_plane *plane; struct drm_plane *plane;
u32 crc32 = 0; 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) { drm_for_each_plane(plane, &vdev->drm) {
struct vkms_plane_state *vplane_state; struct vkms_plane_state *vplane_state;
...@@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work) ...@@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work)
if (primary_crc) if (primary_crc)
crc32 = _vkms_get_crc(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) static int vkms_crc_parse_source(const char *src_name, bool *enabled)
......
...@@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output) ...@@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output)
DRM_ERROR("vkms failure on handling vblank"); DRM_ERROR("vkms failure on handling vblank");
if (state && output->crc_enabled) { if (state && output->crc_enabled) {
state->n_frame = drm_crtc_accurate_vblank_count(crtc); u64 frame = drm_crtc_accurate_vblank_count(crtc);
queue_work(output->crc_workq, &state->crc_work);
/* 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); spin_unlock(&output->lock);
...@@ -211,6 +222,7 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, ...@@ -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); drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);
spin_lock_init(&vkms_out->lock); spin_lock_init(&vkms_out->lock);
spin_lock_init(&vkms_out->state_lock);
vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0); vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0);
......
...@@ -39,12 +39,14 @@ struct vkms_plane_state { ...@@ -39,12 +39,14 @@ struct vkms_plane_state {
* vkms_crtc_state - Driver specific CRTC state * vkms_crtc_state - Driver specific CRTC state
* @base: base CRTC state * @base: base CRTC state
* @crc_work: work struct to compute and add CRC entries * @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 vkms_crtc_state {
struct drm_crtc_state base; struct drm_crtc_state base;
struct work_struct crc_work; struct work_struct crc_work;
unsigned int n_frame; u64 frame_start;
u64 frame_end;
}; };
struct vkms_output { struct vkms_output {
...@@ -59,6 +61,8 @@ struct vkms_output { ...@@ -59,6 +61,8 @@ struct vkms_output {
struct workqueue_struct *crc_workq; struct workqueue_struct *crc_workq;
/* protects concurrent access to crc_data */ /* protects concurrent access to crc_data */
spinlock_t lock; spinlock_t lock;
/* protects concurrent access to crtc_state */
spinlock_t state_lock;
}; };
struct vkms_device { struct vkms_device {
......
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