[PATCH v2] drm/ingenic: Fix missing platform_driver_unregister() call in ingenic_drm_init()

[PATCH v2] drm/ingenic: Fix missing platform_driver_unregister() call in ingenic_drm_init()

[Yuan Can]

A problem about modprobe ingenic-drm failed is triggered with the following
log given:

 [  303.561088] Error: Driver 'ingenic-ipu' is already registered, aborting...
 modprobe: ERROR: could not insert 'ingenic_drm': Device or resource busy

The reason is that ingenic_drm_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without unregistering ingenic_ipu_driver_ptr, resulting
the ingenic-drm can never be installed later.
A simple call graph is shown as below:

 ingenic_drm_init()
   platform_driver_register() # ingenic_ipu_driver_ptr are registered
   platform_driver_register()
     driver_register()
       bus_add_driver()
         priv = kzalloc(...) # OOM happened
   # return without unregister ingenic_ipu_driver_ptr

Fixing this problem by checking the return value of
platform_driver_register() and do platform_unregister_drivers() if
error happened.

Fixes: fc1acf317b01 ("drm/ingenic: Add support for the IPU")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Cc: stable@vger.kernel.org
---
Changes in v2:
- Add missing Cc: stable@vger.kernel.org

 drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
index ab0515d2c420..4499a04f7c13 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
@@ -1629,7 +1629,11 @@ static int ingenic_drm_init(void)
 			return err;
 	}
 
-	return platform_driver_register(&ingenic_drm_driver);
+	err = platform_driver_register(&ingenic_drm_driver);
+	if (IS_ENABLED(CONFIG_DRM_INGENIC_IPU) && err)
+		platform_driver_unregister(ingenic_ipu_driver_ptr);
+
+	return err;
 }
 module_init(ingenic_drm_init);
 
-- 
2.17.1

Re: [PATCH v2] drm/ingenic: Fix missing platform_driver_unregister() call in ingenic_drm_init()

[Paul Cercueil]

Hi,

Le ven. 4 nov. 2022 à 06:45:12 +0000, Yuan Can <yuancan@huawei.com> a 
écrit :
> A problem about modprobe ingenic-drm failed is triggered with the 
> following
> log given:
> 
>  [  303.561088] Error: Driver 'ingenic-ipu' is already registered, 
> aborting...
>  modprobe: ERROR: could not insert 'ingenic_drm': Device or resource 
> busy
> 
> The reason is that ingenic_drm_init() returns 
> platform_driver_register()
> directly without checking its return value, if 
> platform_driver_register()
> failed, it returns without unregistering ingenic_ipu_driver_ptr, 
> resulting
> the ingenic-drm can never be installed later.
> A simple call graph is shown as below:
> 
>  ingenic_drm_init()
>    platform_driver_register() # ingenic_ipu_driver_ptr are registered
>    platform_driver_register()
>      driver_register()
>        bus_add_driver()
>          priv = kzalloc(...) # OOM happened
>    # return without unregister ingenic_ipu_driver_ptr
> 
> Fixing this problem by checking the return value of
> platform_driver_register() and do platform_unregister_drivers() if
> error happened.
> 
> Fixes: fc1acf317b01 ("drm/ingenic: Add support for the IPU")
> Signed-off-by: Yuan Can <yuancan@huawei.com>
> Cc: stable@vger.kernel.org

Applied, thanks!

Cheers,
-Paul

> ---
> Changes in v2:
> - Add missing Cc: stable@vger.kernel.org
> 
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c 
> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index ab0515d2c420..4499a04f7c13 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -1629,7 +1629,11 @@ static int ingenic_drm_init(void)
>  			return err;
>  	}
> 
> -	return platform_driver_register(&ingenic_drm_driver);
> +	err = platform_driver_register(&ingenic_drm_driver);
> +	if (IS_ENABLED(CONFIG_DRM_INGENIC_IPU) && err)
> +		platform_driver_unregister(ingenic_ipu_driver_ptr);
> +
> +	return err;
>  }
>  module_init(ingenic_drm_init);
> 
> --
> 2.17.1
>