On Sat, 9 Mar 2013 19:16:47 +0100, Lars-Peter Clausen wrote:
> i2c_del_adapter() is usually called from a drivers remove callback. The Linux
> device driver model does not allow the remove callback to fail and all resources
> allocated in the probe callback need to be freed, as well as all resources which
> have been provided to the rest of the kernel(for example a I2C adapter) need to
> be revoked. So any function revoking such resources isn't allowed to fail
> either. i2c_del_adapter() adheres to this requirement and will never fail. But
> i2c_del_adapter()'s return type is int, which may cause driver authors to think
> that it can fail. This led to code constructs like:
>
> ret = i2c_del_adapter(...);
> BUG_ON(ret);
>
> Since i2c_del_adapter() always returns 0 the BUG_ON is never hit and essentially
> becomes dead code, which means it can be removed. Making the return type of
> i2c_del_adapter() void makes it explicit that the function will never fail and
> should prevent constructs like the above from re-appearing in the kernel code.
>
> All callers of i2c_del_adapter() have already been updated in a previous patch
> to ignore the return value, so the conversion of the return type from int to
> void can be done without causing any build failures.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> ---
> drivers/i2c/i2c-core.c | 6 ++----
> include/linux/i2c.h | 2 +-
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 7727d33..838d030 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1060,7 +1060,7 @@ static int __process_removed_adapter(struct device_driver *d, void *data)
> * This unregisters an I2C adapter which was previously registered
> * by @i2c_add_adapter or @i2c_add_numbered_adapter.
> */
> -int i2c_del_adapter(struct i2c_adapter *adap)
> +void i2c_del_adapter(struct i2c_adapter *adap)
> {
> struct i2c_adapter *found;
> struct i2c_client *client, *next;
> @@ -1072,7 +1072,7 @@ int i2c_del_adapter(struct i2c_adapter *adap)
> if (found != adap) {
> pr_debug("i2c-core: attempting to delete unregistered "
> "adapter [%s]\n", adap->name);
> - return 0;
> + return;
> }
>
> /* Tell drivers about this removal */
> @@ -1124,8 +1124,6 @@ int i2c_del_adapter(struct i2c_adapter *adap)
> /* Clear the device structure in case this adapter is ever going to be
> added again */
> memset(&adap->dev, 0, sizeof(adap->dev));
> -
> - return 0;
> }
> EXPORT_SYMBOL(i2c_del_adapter);
>
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 8ffab3f..dec1702 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -447,7 +447,7 @@ void i2c_unlock_adapter(struct i2c_adapter *);
> */
> #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
> extern int i2c_add_adapter(struct i2c_adapter *);
> -extern int i2c_del_adapter(struct i2c_adapter *);
> +extern void i2c_del_adapter(struct i2c_adapter *);
> extern int i2c_add_numbered_adapter(struct i2c_adapter *);
>
> extern int i2c_register_driver(struct module *, struct i2c_driver *);
Reviewed-by: Jean Delvare <khali@xxxxxxxxxxxx>
--
Jean Delvare
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
