linux-kernel - Re: [PATCH 1/7] bus: mhi: core: Pass module owner during client driver registration

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Message-ID: <20200323190506.GB119913@minitux>
Date:   Mon, 23 Mar 2020 12:05:06 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     gregkh@...uxfoundation.org, davem@...emloft.net,
        smohanad@...eaurora.org, jhugo@...eaurora.org,
        kvalo@...eaurora.org, hemantk@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] bus: mhi: core: Pass module owner during client
 driver registration

On Mon 23 Mar 05:21 PDT 2020, Manivannan Sadhasivam wrote:

> The module owner field can be used to prevent the removal of kernel
> modules when there are any device files associated with it opened in
> userspace. Hence, modify the API to pass module owner field. For
> convenience, module_mhi_driver() macro is used which takes care of
> passing the module owner through THIS_MODULE of the module of the
> driver and also avoiding the use of specifying the default MHI client
> driver register/unregister routines.
> 
> Suggested-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

> ---
>  drivers/bus/mhi/core/init.c |  5 +++--
>  include/linux/mhi.h         | 19 ++++++++++++++++++-
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index 5fb756ca335e..eb7f556a8531 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -1189,7 +1189,7 @@ static int mhi_driver_remove(struct device *dev)
>  	return 0;
>  }
>  
> -int mhi_driver_register(struct mhi_driver *mhi_drv)
> +int __mhi_driver_register(struct mhi_driver *mhi_drv, struct module *owner)
>  {
>  	struct device_driver *driver = &mhi_drv->driver;
>  
> @@ -1197,12 +1197,13 @@ int mhi_driver_register(struct mhi_driver *mhi_drv)
>  		return -EINVAL;
>  
>  	driver->bus = &mhi_bus_type;
> +	driver->owner = owner;
>  	driver->probe = mhi_driver_probe;
>  	driver->remove = mhi_driver_remove;
>  
>  	return driver_register(driver);
>  }
> -EXPORT_SYMBOL_GPL(mhi_driver_register);
> +EXPORT_SYMBOL_GPL(__mhi_driver_register);
>  
>  void mhi_driver_unregister(struct mhi_driver *mhi_drv)
>  {
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 79cb9f898544..0e7071dbf2c3 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -514,11 +514,28 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
>   */
>  void mhi_unregister_controller(struct mhi_controller *mhi_cntrl);
>  
> +/*
> + * module_mhi_driver() - Helper macro for drivers that don't do
> + * anything special in module init/exit.  This eliminates a lot of
> + * boilerplate.  Each module may only use this macro once, and
> + * calling it replaces module_init() and module_exit()
> + */
> +#define module_mhi_driver(mhi_drv) \
> +	module_driver(mhi_drv, mhi_driver_register, \
> +		      mhi_driver_unregister)
> +
> +/*
> + * Macro to avoid include chaining to get THIS_MODULE
> + */
> +#define mhi_driver_register(mhi_drv) \
> +	__mhi_driver_register(mhi_drv, THIS_MODULE)
> +
>  /**
>   * mhi_driver_register - Register driver with MHI framework
>   * @mhi_drv: Driver associated with the device
> + * @owner: The module owner
>   */
> -int mhi_driver_register(struct mhi_driver *mhi_drv);
> +int __mhi_driver_register(struct mhi_driver *mhi_drv, struct module *owner);
>  
>  /**
>   * mhi_driver_unregister - Unregister a driver for mhi_devices
> -- 
> 2.17.1
>