[PATCH 7/7] cxl: Fix double unregistration of CXL regions for type2 devices

[Dave Jiang <dave.jiang@intel.com>]

For a type2 device cxl_memdev_attach_region() is provided as the callback
to devm_cxl_add_memdev() call. In cxl_memdev_attach_region() a devm
action cxl_endpoint_region_autoremove() is registered to remove the
region when the device is removed. And this action calls
unregister_region() on trigger.

When the endpoint port driver is probed, discover_region() is called
to register a region. The call tree becomes discover_region() ->
cxl_add_to_region() -> construct_region() -> __create_region() ->
devm_cxl_add_region(). In devm_cxl_add_region(), unregister_region()
is also added as a devm action.

When removing the cxl_test module, the platform devices are removed
and that triggers the endpoint driver removal and calling of
unregister_region(). And then when the mock type2 device driver is being
removed, the devm action of unregister_region() is called again, which
causes a kernel warning about double unregistration of the same region.
Add a check to see if the devm action is already removed before calling
unregister_region() for cxl_endpoint_region_autoremove().

Signed-off-by: Dave Jiang <dave.jiang@intel.com>

---
- Need to add a fixes tag when the patch commit that introduces
  cxl_endpoint_region_autoremove() is stable.
---
 drivers/cxl/core/region.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 61a3efdbf3c9..1a7c0895bb88 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -4296,7 +4296,8 @@ static void cxl_endpoint_region_autoremove(void *_cxlr)
 	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
 	struct cxl_port *port = cxlrd_to_port(cxlrd);
 
-	devm_release_action(port->uport_dev, unregister_region, cxlr);
+	if (!devm_remove_action_nowarn(port->uport_dev, unregister_region, cxlr))
+		unregister_region(cxlr);
 }
 
 /*
-- 
2.53.0