A problem about modprobe vc4 failed is triggered with the following log
given:
[ 420.327987] Error: Driver 'vc4_hvs' is already registered, aborting...
[ 420.333904] failed to register platform driver vc4_hvs_driver [vc4]: -16
modprobe: ERROR: could not insert 'vc4': Device or resource busy
The reason is that vc4_drm_register() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
fails, it returns without unregistering all the vc4 drivers, resulting the
vc4 can never be installed later.
A simple call graph is shown as below:
vc4_drm_register()
platform_register_drivers() # all vc4 drivers are registered
platform_driver_register()
driver_register()
bus_add_driver()
priv = kzalloc(...) # OOM happened
# return without unregister drivers
Fixing this problem by checking the return value of
platform_driver_register() and do platform_unregister_drivers() if
error happened.
Fixes: c8b75bca92cb ("drm/vc4: Add KMS support for Raspberry Pi.")
Signed-off-by: Yuan Can <yuancan@xxxxxxxxxx>
---
drivers/gpu/drm/vc4/vc4_drv.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 2027063fdc30..8c329c071c62 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -476,7 +476,12 @@ static int __init vc4_drm_register(void)
if (ret)
return ret;
- return platform_driver_register(&vc4_platform_driver);
+ ret = platform_driver_register(&vc4_platform_driver);
+ if (ret)
+ platform_unregister_drivers(component_drivers,
+ ARRAY_SIZE(component_drivers));
+
+ return ret;
}
static void __exit vc4_drm_unregister(void)
--
2.17.1
