Re: [PATCH v3 1/3] i2c: core: improve return value handling of i2c_new_device and i2c_new_dummy

Bartosz Golaszewski
2017-12-14T20:39:33Z

2017-12-13 20:11 GMT+01:00 Heiner Kallweit <hkallweit1@gmail.com>:
> Currently i2c_new_device and i2c_new_dummy return just NULL in error
> case although they have more error details internally. Therefore move
> the functionality into new functions returning detailed errors and
> add wrappers for compatibilty with the current API.
>
> This allows to use these functions with detailed error codes within
> the i2c core or for API extensions.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> v3:
> - prefix i2c_new_device and i2c_new_dummy with two underscores
> instead one
> ---
> drivers/i2c/i2c-core-base.c | 46 ++++++++++++++++++++++++++++++++-------------
> 1 file changed, 33 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index bb34a5d41..3faa9b1d3 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -656,7 +656,7 @@ static int i2c_dev_irq_from_resources(const struct resource *resources,
> }
>
> /**
> - * i2c_new_device - instantiate an i2c device
> + * __i2c_new_device - instantiate an i2c device
> * @adap: the adapter managing the device
> * @info: describes one I2C device; bus_num is ignored
> * Context: can sleep
> @@ -669,17 +669,17 @@ static int i2c_dev_irq_from_resources(const struct resource *resources,
> * before any i2c_adapter could exist.
> *
> * This returns the new i2c client, which may be saved for later use with
> - * i2c_unregister_device(); or NULL to indicate an error.
> + * i2c_unregister_device(); or an ERR_PTR to indicate an error.
> */
> -struct i2c_client *
> -i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> +static struct i2c_client *
> +__i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> {
> struct i2c_client *client;
> int status;
>
> client = kzalloc(sizeof *client, GFP_KERNEL);
> if (!client)
> - return NULL;
> + return ERR_PTR(-ENOMEM);
>
> client->adapter = adap;
>
> @@ -746,7 +746,17 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> client->name, client->addr, status);
> out_err_silent:
> kfree(client);
> - return NULL;
> + return ERR_PTR(status);
> +}
> +
> +/* wrapper to be compatible with the current API */

This function is part of the i2c API, so it still needs to be
documented with a proper kernel doc.

After fixing that:

Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>

> +struct i2c_client *
> +i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> +{
> + struct i2c_client *ret;
> +
> + ret = __i2c_new_device(adap, info);
> + return IS_ERR(ret) ? NULL : ret;
> }
> EXPORT_SYMBOL_GPL(i2c_new_device);
>
> @@ -793,7 +803,7 @@ static struct i2c_driver dummy_driver = {
> };
>
> /**
> - * i2c_new_dummy - return a new i2c device bound to a dummy driver
> + * __i2c_new_dummy - return a new i2c device bound to a dummy driver
> * @adapter: the adapter managing the device
> * @address: seven bit address to be used
> * Context: can sleep
> @@ -808,15 +818,25 @@ static struct i2c_driver dummy_driver = {
> * different driver.
> *
> * This returns the new i2c client, which should be saved for later use with
> - * i2c_unregister_device(); or NULL to indicate an error.
> + * i2c_unregister_device(); or an ERR_PTR to indicate an error.
> */
> -struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
> +static struct i2c_client *
> +__i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
> {
> struct i2c_board_info info = {
> I2C_BOARD_INFO("dummy", address),
> };
>
> - return i2c_new_device(adapter, &info);
> + return __i2c_new_device(adapter, &info);
> +}
> +
> +/* wrapper to be compatible with the current API */
> +struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
> +{
> + struct i2c_client *ret;
> +
> + ret = __i2c_new_dummy(adapter, address);
> + return IS_ERR(ret) ? NULL : ret;
> }
> EXPORT_SYMBOL_GPL(i2c_new_dummy);
>
> @@ -939,9 +959,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
> info.flags |= I2C_CLIENT_SLAVE;
> }
>
> - client = i2c_new_device(adap, &info);
> - if (!client)
> - return -EINVAL;
> + client = __i2c_new_device(adap, &info);
> + if (IS_ERR(client))
> + return PTR_ERR(client);
>
> /* Keep track of the added device */
> mutex_lock(&adap->userspace_clients_lock);
> --
> 2.15.1
>
>
>