drm/amd/display: Fix writeback job lock evasion within dm_crtc_high_irq

[Why]
Coverity report LOCK_EVASION warning. Access
acrtc->wb_pending without lock wb_conn->job_lock.

[How]
Lock wb_conn->job_lock before accessing
acrtc->wb_pending.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index ee8da59..5667db1 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -597,12 +597,14 @@ static void dm_crtc_high_irq(void *interrupt_params)
        if (!acrtc)
                return;
 
-       if (acrtc->wb_pending) {
-               if (acrtc->wb_conn) {
-                       spin_lock_irqsave(&acrtc->wb_conn->job_lock, flags);
+       if (acrtc->wb_conn) {
+               spin_lock_irqsave(&acrtc->wb_conn->job_lock, flags);
+
+               if (acrtc->wb_pending) {
                        job = list_first_entry_or_null(&acrtc->wb_conn->job_queue,
                                                       struct drm_writeback_job,
                                                       list_entry);
+                       acrtc->wb_pending = false;
                        spin_unlock_irqrestore(&acrtc->wb_conn->job_lock, flags);
 
                        if (job) {
@@ -620,8 +622,7 @@ static void dm_crtc_high_irq(void *interrupt_params)
                                                               acrtc->dm_irq_params.stream, 0);
                        }
                } else
-                       DRM_ERROR("%s: no amdgpu_crtc wb_conn\n", __func__);
-               acrtc->wb_pending = false;
+                       spin_unlock_irqrestore(&acrtc->wb_conn->job_lock, flags);
        }
 
        vrr_active = amdgpu_dm_crtc_vrr_active_irq(acrtc);