Modules registering driver with register_virtio_driver() might forget to
set .owner field. i2c-virtio.c for example has it missing. The field
is used by some of other kernel parts for reference counting
(try_module_get()), so it is expected that drivers will set it.
Solve the problem by moving this task away from the drivers to the core
amba bus code, just like we did for platform_driver in
commit 9447057eaff8 ("platform_device: use a macro instead of
platform_driver_register").
Signed-off-by: Krzysztof Kozlowski <[email protected]>
---
Documentation/driver-api/virtio/writing_virtio_drivers.rst | 1 -
drivers/virtio/virtio.c | 6 ++++--
include/linux/virtio.h | 7 +++++--
3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/Documentation/driver-api/virtio/writing_virtio_drivers.rst b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
index e14c58796d25..e5de6f5d061a 100644
--- a/Documentation/driver-api/virtio/writing_virtio_drivers.rst
+++ b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
@@ -97,7 +97,6 @@ like this::
static struct virtio_driver virtio_dummy_driver = {
.driver.name = KBUILD_MODNAME,
- .driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtio_dummy_probe,
.remove = virtio_dummy_remove,
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index f173587893cb..9510c551dce8 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -362,14 +362,16 @@ static const struct bus_type virtio_bus = {
.remove = virtio_dev_remove,
};
-int register_virtio_driver(struct virtio_driver *driver)
+int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
{
/* Catch this early. */
BUG_ON(driver->feature_table_size && !driver->feature_table);
driver->driver.bus = &virtio_bus;
+ driver->driver.owner = owner;
+
return driver_register(&driver->driver);
}
-EXPORT_SYMBOL_GPL(register_virtio_driver);
+EXPORT_SYMBOL_GPL(__register_virtio_driver);
void unregister_virtio_driver(struct virtio_driver *driver)
{
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b0201747a263..26c4325aa373 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -170,7 +170,7 @@ size_t virtio_max_dma_size(const struct virtio_device *vdev);
/**
* struct virtio_driver - operations for a virtio I/O driver
- * @driver: underlying device driver (populate name and owner).
+ * @driver: underlying device driver (populate name).
* @id_table: the ids serviced by this driver.
* @feature_table: an array of feature numbers supported by this driver.
* @feature_table_size: number of entries in the feature table array.
@@ -208,7 +208,10 @@ static inline struct virtio_driver *drv_to_virtio(struct device_driver *drv)
return container_of(drv, struct virtio_driver, driver);
}
-int register_virtio_driver(struct virtio_driver *drv);
+/* use a macro to avoid include chaining to get THIS_MODULE */
+#define register_virtio_driver(drv) \
+ __register_virtio_driver(drv, THIS_MODULE)
+int __register_virtio_driver(struct virtio_driver *drv, struct module *owner);
void unregister_virtio_driver(struct virtio_driver *drv);
/* module_virtio_driver() - Helper macro for drivers that don't do
--
2.34.1
On 29/03/2024 12:42, Stefano Garzarella wrote:
>> };
>>
>> -int register_virtio_driver(struct virtio_driver *driver)
>> +int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
>> {
>> /* Catch this early. */
>> BUG_ON(driver->feature_table_size && !driver->feature_table);
>> driver->driver.bus = &virtio_bus;
>> + driver->driver.owner = owner;
>> +
>
> `.driver.name = KBUILD_MODNAME` also seems very common, should we put
> that in the macro as well?
This is a bit different thing. Every driver is expected to set owner to
itself (THIS_MODULE), but is every driver name KBUILD_MODNAME? Remember
that this overrides whatever driver actually put there.
Best regards,
Krzysztof
On Wed, Mar 27, 2024 at 01:40:54PM +0100, Krzysztof Kozlowski wrote:
> Modules registering driver with register_virtio_driver() might forget to
> set .owner field. i2c-virtio.c for example has it missing. The field
> is used by some of other kernel parts for reference counting
> (try_module_get()), so it is expected that drivers will set it.
>
> Solve the problem by moving this task away from the drivers to the core
> amba bus code, just like we did for platform_driver in
> commit 9447057eaff8 ("platform_device: use a macro instead of
> platform_driver_register").
>
> Signed-off-by: Krzysztof Kozlowski <[email protected]>
This makes sense. So this will be:
Fixes: 3cfc88380413 ("i2c: virtio: add a virtio i2c frontend driver")
Cc: "Jie Deng" <[email protected]>
and I think I will pick this patch for this cycle to fix
the bug. The cleanups can go in the next cycle.
> ---
> Documentation/driver-api/virtio/writing_virtio_drivers.rst | 1 -
> drivers/virtio/virtio.c | 6 ++++--
> include/linux/virtio.h | 7 +++++--
> 3 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/driver-api/virtio/writing_virtio_drivers.rst b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
> index e14c58796d25..e5de6f5d061a 100644
> --- a/Documentation/driver-api/virtio/writing_virtio_drivers.rst
> +++ b/Documentation/driver-api/virtio/writing_virtio_drivers.rst
> @@ -97,7 +97,6 @@ like this::
>
> static struct virtio_driver virtio_dummy_driver = {
> .driver.name = KBUILD_MODNAME,
> - .driver.owner = THIS_MODULE,
> .id_table = id_table,
> .probe = virtio_dummy_probe,
> .remove = virtio_dummy_remove,
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index f173587893cb..9510c551dce8 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -362,14 +362,16 @@ static const struct bus_type virtio_bus = {
> .remove = virtio_dev_remove,
> };
>
> -int register_virtio_driver(struct virtio_driver *driver)
> +int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
> {
> /* Catch this early. */
> BUG_ON(driver->feature_table_size && !driver->feature_table);
> driver->driver.bus = &virtio_bus;
> + driver->driver.owner = owner;
> +
> return driver_register(&driver->driver);
> }
> -EXPORT_SYMBOL_GPL(register_virtio_driver);
> +EXPORT_SYMBOL_GPL(__register_virtio_driver);
>
> void unregister_virtio_driver(struct virtio_driver *driver)
> {
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index b0201747a263..26c4325aa373 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -170,7 +170,7 @@ size_t virtio_max_dma_size(const struct virtio_device *vdev);
>
> /**
> * struct virtio_driver - operations for a virtio I/O driver
> - * @driver: underlying device driver (populate name and owner).
> + * @driver: underlying device driver (populate name).
> * @id_table: the ids serviced by this driver.
> * @feature_table: an array of feature numbers supported by this driver.
> * @feature_table_size: number of entries in the feature table array.
> @@ -208,7 +208,10 @@ static inline struct virtio_driver *drv_to_virtio(struct device_driver *drv)
> return container_of(drv, struct virtio_driver, driver);
> }
>
> -int register_virtio_driver(struct virtio_driver *drv);
> +/* use a macro to avoid include chaining to get THIS_MODULE */
> +#define register_virtio_driver(drv) \
> + __register_virtio_driver(drv, THIS_MODULE)
> +int __register_virtio_driver(struct virtio_driver *drv, struct module *owner);
> void unregister_virtio_driver(struct virtio_driver *drv);
>
> /* module_virtio_driver() - Helper macro for drivers that don't do
>
> --
> 2.34.1