| Message ID | 20240327-module-owner-virtio-v1-1-0feffab77d99@linaro.org |
|---|---|
| State | Accepted |
| Commit | ffe6176b7f53ca0c99355f13e14a33a40cf49406 |
| Headers | show |
| Series | virtio: store owner from modules with register_virtio_driver() | expand |
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 <krzysztof.kozlowski@linaro.org> >--- > 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; >+ `.driver.name = KBUILD_MODNAME` also seems very common, should we put that in the macro as well? > 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 Fri, Mar 29, 2024 at 01:07:31PM +0100, Krzysztof Kozlowski wrote: >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? Nope, IIUC we have 2 exceptions: - drivers/firmware/arm_scmi/virtio.c - arch/um/drivers/virt-pci.c >Remember that this overrides whatever driver actually put there. They can call __register_virtio_driver() where we can add the `name` parameter. That said, I don't have a strong opinion, we can leave it as it is. Thanks, Stefano
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
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 <krzysztof.kozlowski@linaro.org> --- 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(-)