[PATCH 13/23] drm/amd/display: Fix secure display lock problems

[Solomon Chiu]

From: Wayne Lin <Wayne.Lin at amd.com>

[Why]
Find out few locks problems while doing secure display. They are
following few parts:

1. crc_rd_work_lock in amdgpu_dm_crtc_handle_crc_window_irq() should
also use spin_lock_irqsave instead of spin_lock_irq.

2. In crc_win_update_set(), crc_rd_work_lock should be grabbed after
obtaining lock event_lock. Otherwise, will cause deadlock by conflicting
the lock order in amdgpu_dm_crtc_handle_crc_window_irq()

3. flush_work() in crc_win_update_set() is no need and will cause
deadlock since amdgpu_dm_crtc_notify_ta_to_read() also tries to grab
lock crc_rd_work_lock.

[How]
Fix above problems.

Signed-off-by: Wayne Lin <Wayne.Lin at amd.com>
Reviewed-by: Solomon Chiu <Solomon.Chiu at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c  | 10 +++++-----
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c  |  6 ++----
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
index 3adbaf50a558..c6d6baab106e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c
@@ -433,7 +433,7 @@ void amdgpu_dm_crtc_handle_crc_window_irq(struct drm_crtc *crtc)
 	struct amdgpu_device *adev = NULL;
 	struct crc_rd_work *crc_rd_wrk = NULL;
 	struct crc_params *crc_window = NULL, tmp_window;
-	unsigned long flags;
+	unsigned long flags1, flags2;
 	struct crtc_position position;
 	uint32_t v_blank;
 	uint32_t v_back_porch;
@@ -447,7 +447,7 @@ void amdgpu_dm_crtc_handle_crc_window_irq(struct drm_crtc *crtc)
 	adev = drm_to_adev(crtc->dev);
 	drm_dev = crtc->dev;
 
-	spin_lock_irqsave(&drm_dev->event_lock, flags);
+	spin_lock_irqsave(&drm_dev->event_lock, flags1);
 	stream_state = acrtc->dm_irq_params.stream;
 	cur_crc_src = acrtc->dm_irq_params.crc_src;
 	timing_out = &stream_state->timing;
@@ -508,10 +508,10 @@ void amdgpu_dm_crtc_handle_crc_window_irq(struct drm_crtc *crtc)
 				if (acrtc->dm_irq_params.crc_window.skip_frame_cnt == 0) {
 					if (adev->dm.crc_rd_wrk) {
 						crc_rd_wrk = adev->dm.crc_rd_wrk;
-						spin_lock_irq(&crc_rd_wrk->crc_rd_work_lock);
+						spin_lock_irqsave(&crc_rd_wrk->crc_rd_work_lock, flags2);
 						crc_rd_wrk->phy_inst =
 							stream_state->link->link_enc_hw_inst;
-						spin_unlock_irq(&crc_rd_wrk->crc_rd_work_lock);
+						spin_unlock_irqrestore(&crc_rd_wrk->crc_rd_work_lock, flags2);
 						schedule_work(&crc_rd_wrk->notify_ta_work);
 					}
 				} else {
@@ -522,7 +522,7 @@ void amdgpu_dm_crtc_handle_crc_window_irq(struct drm_crtc *crtc)
 	}
 
 cleanup:
-	spin_unlock_irqrestore(&drm_dev->event_lock, flags);
+	spin_unlock_irqrestore(&drm_dev->event_lock, flags1);
 }
 
 void amdgpu_dm_crtc_secure_display_resume(struct amdgpu_device *adev)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index 6d839d3fb6a3..b8644f49e0f2 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -2695,14 +2695,12 @@ static int crc_win_update_set(void *data, u64 val)
 	struct crc_rd_work *crc_rd_wrk = adev->dm.crc_rd_wrk;
 
 	if (val) {
-		spin_lock_irq(&crc_rd_wrk->crc_rd_work_lock);
 		spin_lock_irq(&adev_to_drm(adev)->event_lock);
+		spin_lock_irq(&crc_rd_wrk->crc_rd_work_lock);
 		if (crc_rd_wrk && crc_rd_wrk->crtc) {
 			old_crtc = crc_rd_wrk->crtc;
 			old_acrtc = to_amdgpu_crtc(old_crtc);
-			flush_work(&adev->dm.crc_rd_wrk->notify_ta_work);
 		}
-
 		new_acrtc = to_amdgpu_crtc(new_crtc);
 
 		if (old_crtc && old_crtc != new_crtc) {
@@ -2720,8 +2718,8 @@ static int crc_win_update_set(void *data, u64 val)
 			new_acrtc->dm_irq_params.crc_window.skip_frame_cnt = 0;
 			crc_rd_wrk->crtc = new_crtc;
 		}
-		spin_unlock_irq(&adev_to_drm(adev)->event_lock);
 		spin_unlock_irq(&crc_rd_wrk->crc_rd_work_lock);
+		spin_unlock_irq(&adev_to_drm(adev)->event_lock);
 	}
 
 	return 0;
-- 
2.29.0