Am 02.11.23 um 14:08 schrieb Thomas Zimmermann:
Do not acquire a reference on the module that provides a client's callback functions in drm_client_init(). The additional reference prevents the user from unloading the callback functions' module and thus creating dangling pointers. This is only necessary if there is no direct dependency between the caller of drm_client_init() and the provider of the callbacks in struct drm_client_funcs. If this case ever existed, it has been removed from the DRM code. Callers of drm_client_init() also provide the callback implementation. The lifetime of the clients is tied to the dependency chain's outer-most module, which is the hardware's DRM driver. Before client helpers could be unloaded, the driver module would have to be unloaded, which also unregisters all clients. Driver modules that set up DRM clients can now be unloaded. Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> Acked-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
I've added this patch to drm-misc-next.
--- drivers/gpu/drm/drm_client.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c index c3027115d0552..9403b3f576f7b 100644 --- a/drivers/gpu/drm/drm_client.c +++ b/drivers/gpu/drm/drm_client.c @@ -5,7 +5,6 @@#include <linux/iosys-map.h>#include <linux/list.h> -#include <linux/module.h> #include <linux/mutex.h> #include <linux/seq_file.h> #include <linux/slab.h> @@ -84,16 +83,13 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client, if (!drm_core_check_feature(dev, DRIVER_MODESET) || !dev->driver->dumb_create) return -EOPNOTSUPP;- if (funcs && !try_module_get(funcs->owner))- return -ENODEV; - client->dev = dev; client->name = name; client->funcs = funcs;ret = drm_client_modeset_create(client);if (ret) - goto err_put_module; + return ret;ret = drm_client_open(client);if (ret) @@ -105,10 +101,6 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,err_free:drm_client_modeset_free(client); -err_put_module: - if (funcs) - module_put(funcs->owner); - return ret; } EXPORT_SYMBOL(drm_client_init); @@ -177,8 +169,6 @@ void drm_client_release(struct drm_client_dev *client) drm_client_modeset_free(client); drm_client_close(client); drm_dev_put(dev); - if (client->funcs) - module_put(client->funcs->owner); } EXPORT_SYMBOL(drm_client_release);
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)
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