[PATCH v2 2/2] dma-buf/sw_sync: force signal all unsignaled fences on dying timeline

[Gustavo Padovan]

From: Dominik Behr <dbehr at chromium.org>

To avoid hanging userspace components that might have been waiting on the
active fences of the destroyed timeline we need to signal with error all
remaining fences on such timeline.

This restore the default behaviour of the Android sw_sync framework, which
Android still relies on. It was broken on the dma fence conversion a few
years ago and never fixed.

v2: Do not bother with cleanup do the list (Chris Wilson)

Signed-off-by: Dominik Behr <dbehr at chromium.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.com>
---
 drivers/dma-buf/sw_sync.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 38cc7389a6c1..f183eef074fd 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -321,9 +321,19 @@ static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
 static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
 {
 	struct sync_timeline *obj = file->private_data;
+	struct sync_pt *pt, *next;
 
 	smp_wmb();
 
+	spin_lock_irq(&obj->lock);
+
+	list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
+		dma_fence_set_error(&pt->base, -ENOENT);
+		dma_fence_signal_locked(&pt->base);
+	}
+
+	spin_unlock_irq(&obj->lock);
+
 	sync_timeline_put(obj);
 	return 0;
 }
-- 
2.13.5