On Wed, Dec 22, 2021 at 08:44:44AM +0100, Greg Kroah-Hartman wrote:
On Tue, Dec 21, 2021 at 06:46:01PM +0100, Rafał Miłecki wrote:
On 21.12.2021 17:06, Greg Kroah-Hartman wrote:
On Tue, Dec 21, 2021 at 04:45:50PM +0100, Rafał Miłecki wrote:
From: Rafał Miłecki <rafal@xxxxxxxxxx>
1. Drop incorrect put_device() calls
If device_register() fails then underlaying device_add() takes care of
calling put_device() if needed. There is no need to do that in a driver.
Did you read the documentation for device_register() that says:
* NOTE: _Never_ directly free @dev after calling this function, even
* if it returned an error! Always use put_device() to give up the
* reference initialized in this function instead.
I clearly tried to be too smart and ignored documentation.
I'd say device_add() behaviour is rather uncommon and a bit unintuitive.
Most kernel functions are safe to assume to do nothing that requires
cleanup if they fail.
E.g. if I call platform_device_register() and it fails I don't need to
call anything like platform_device_put(). I just free previously
allocated memory.
And that is wrong.
It seems Rafał is mistaken here too; you certainly need to call
platform_device_put() if platform_device_register() fail, even if many
current users do appear to get this wrong.