[PATCH] gpu: host1x: Detach driver on unregister

* [PATCH] gpu: host1x: Detach driver on unregister
@ 2020-04-08 17:38 ` Thierry Reding
  0 siblings, 0 replies; 4+ messages in thread
From: Thierry Reding @ 2020-04-08 17:38 UTC (permalink / raw)
  To: Thierry Reding
  Cc: dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
	linux-tegra-u79uwXL29TY76Z2rM5mHXA, Sowjanya Komatineni

From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Currently when a host1x device driver is unregistered, it is not
detached from the host1x controller, which means that the device
will stay around and when the driver is registered again, it may
bind to the old, stale device rather than the new one that was
created from scratch upon driver registration. This in turn can
cause various weird crashes within the driver core because it is
confronted with a device that was already deleted.

Fix this by detaching the driver from the host1x controller when
it is unregistered. This ensures that the deleted device also is
no longer present in the device list that drivers will bind to.

Reported-by: Sowjanya Komatineni <skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 drivers/gpu/host1x/bus.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index 6a995db51d6d..e201f62d62c0 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -686,8 +686,17 @@ EXPORT_SYMBOL(host1x_driver_register_full);
  */
 void host1x_driver_unregister(struct host1x_driver *driver)
 {
+	struct host1x *host1x;
+
 	driver_unregister(&driver->driver);
 
+	mutex_lock(&devices_lock);
+
+	list_for_each_entry(host1x, &devices, list)
+		host1x_detach_driver(host1x, driver);
+
+	mutex_unlock(&devices_lock);
+
 	mutex_lock(&drivers_lock);
 	list_del_init(&driver->list);
 	mutex_unlock(&drivers_lock);
-- 
2.24.1

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