On Sat, Apr 23, 2022 at 01:41:30PM +0200, Hans de Goede wrote:
> Hi,
>
> On 4/22/22 18:17, José Expósito wrote:
> > As described in the documentation for devm_input_allocate_device():
> >
> > Managed input devices do not need to be explicitly unregistered or
> > freed as it will be done automatically when owner device unbinds from
> > its driver (or binding fails).
> >
> > However this driver was explicitly freeing the input device, allocated
> > using devm_input_allocate_device() through hidpp_allocate_input().
> >
> > Remove the call to input_free_device() to avoid a possible double free
> > error.
>
> Actually calling input_free_device() on a devm allocated input device
> is fine. The input subsystem has chosen to not have a
> separate devm_input_free_device(), instead input_free_device() knows
> if a device is allocated through devm and then also frees the devres
> tied to it:
>
> void input_free_device(struct input_dev *dev)
> {
> if (dev) {
> if (dev->devres_managed)
> WARN_ON(devres_destroy(dev->dev.parent,
> devm_input_device_release,
> devm_input_device_match,
> dev));
> input_put_device(dev);
> }
> }
Hi Hans,
Thanks for the code review.
Obviously, I completely misunderstood these functions, my bad.
Thanks for the explanation.
Please ignore the patchset.
Jose
> >
> > Fixes: c39e3d5fc9dd3 ("HID: logitech-hidpp: late bind the input device on wireless connection")
> > Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
> > ---
> > drivers/hid/hid-logitech-hidpp.c | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> > index 81de88ab2ecc..9c00a781ab57 100644
> > --- a/drivers/hid/hid-logitech-hidpp.c
> > +++ b/drivers/hid/hid-logitech-hidpp.c
> > @@ -3957,11 +3957,7 @@ static void hidpp_connect_event(struct hidpp_device *hidpp)
> > }
> >
> > hidpp_populate_input(hidpp, input);
> > -
> > - ret = input_register_device(input);
> > - if (ret)
> > - input_free_device(input);
> > -
>
> The original code does look wrong there though, since the input device
> is free-ed it should not be stored in hidpp->delayed_input, so this should be comes:
>
> ret = input_register_device(input);
> if (ret) {
> input_free_device(input);
> return;
> }
>
>
> Regards,
>
> Hans
>
>
> > hidpp->delayed_input = input;
> > }
> >
>
>
