答复: [PATCH] USB: apple-mfi-fastcharge: fix reference leak in apple_mfi_fc_set_property

[zhangqilong <zhangqilong3@huawei.com>]

> 
> On Fri, 2020-10-30 at 23:45 +0800, Zhang Qilong wrote:
> > pm_runtime_get_sync() will increment pm usage counter even it failed.
> > Forgetting to call pm_runtime_put_noidle will result in reference leak
> > in apple_mfi_fc_set_property, so we should fix it.
> >
> > Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
> 
> It looks correct, but I don't know whether it's necessary.
> There's a boatload of users of that API that don't even check for the
> get_sync() retval, and loads more where it's checked but never acted upon.
> 
> Do you intend to fix all those as well?
> 

pm_runtime_get_sync will increase the reference count at first, and it will resume the device
later. If runtime of the device is active or has error(something else....), resume will failed. If we
do not call put operation to decrease the reference, the result is that this device cannot enter
the idle state and always stay busy or other non-idle state, maybe it consumes more power or
raise additional errors... And I'll try to fix them : )

Thanks, best wish!

Zhang Qilong

> > ---
> >  drivers/usb/misc/apple-mfi-fastcharge.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/misc/apple-mfi-fastcharge.c
> > b/drivers/usb/misc/apple-mfi-fastcharge.c
> > index b403094a6b3a..9e1ad4536e36 100644
> > --- a/drivers/usb/misc/apple-mfi-fastcharge.c
> > +++ b/drivers/usb/misc/apple-mfi-fastcharge.c
> > @@ -120,8 +120,10 @@ static int apple_mfi_fc_set_property(struct
> > power_supply *psy,
> >         dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
> >
> >         ret = pm_runtime_get_sync(&mfi->udev->dev);
> > -       if (ret < 0)
> > +       if (ret < 0) {
> > +               pm_runtime_put_noidle(&mfi->udev->dev);
> >                 return ret;
> > +       }
> >
> >         switch (psp) {
> >         case POWER_SUPPLY_PROP_CHARGE_TYPE:
>