[PATCH v8 08/10] drm: writeback: clean up writeback jobs outside the job_lock

[Dmitry Baryshkov]

drm_writeback_connector_cleanup() frees the jobs left on the queue while
holding job_lock with interrupts disabled. drm_writeback_cleanup_job()
may sleep, though: dropping the last framebuffer reference takes
mode_config.idr_mutex and other mutexes, and a driver's
cleanup_writeback_job() hook (e.g. amdgpu) grabs a dma_resv ww_mutex.

Splice the queue onto a local list under the lock and free the jobs after
dropping it, so the sleeping work runs in process context.

Fixes: 1914ba2b91ea ("drm: writeback: Create drmm variants for drm_writeback_connector initialization")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_writeback.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
index 2f6a7b50336c..6487f4a104f2 100644
--- a/drivers/gpu/drm/drm_writeback.c
+++ b/drivers/gpu/drm/drm_writeback.c
@@ -281,18 +281,21 @@ EXPORT_SYMBOL(drm_writeback_connector_init);
 static void drm_writeback_connector_cleanup(struct drm_device *dev,
 					    void *data)
 {
-	unsigned long flags;
-	struct drm_writeback_job *pos, *n;
 	struct drm_writeback_connector *wb_connector = data;
+	struct drm_writeback_job *pos, *n;
+	unsigned long flags;
+	LIST_HEAD(jobs);
 
 	drm_property_blob_put(wb_connector->pixel_formats_blob_ptr);
 
 	spin_lock_irqsave(&wb_connector->job_lock, flags);
-	list_for_each_entry_safe(pos, n, &wb_connector->job_queue, list_entry) {
+	list_splice_init(&wb_connector->job_queue, &jobs);
+	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
+
+	list_for_each_entry_safe(pos, n, &jobs, list_entry) {
 		list_del(&pos->list_entry);
 		drm_writeback_cleanup_job(pos);
 	}
-	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
 }
 
 /**

-- 
2.47.3