linux-kernel - Re: [PATCH] USB: apple-mfi-fastcharge: Use devm

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Date:   Sat, 14 Nov 2020 14:17:48 +0000
From:   Lucas Tanure <tanure@...ux.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Bastien Nocera <hadess@...ess.net>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] USB: apple-mfi-fastcharge: Use devm_kzalloc and simplify
 the code

On Sat, Nov 14, 2020 at 12:56 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Sat, Nov 14, 2020 at 12:42:49PM +0000, Lucas Tanure wrote:
> > Signed-off-by: Lucas Tanure <tanure@...ux.com>
>
> I can't take patches without any changelog text, sorry.
>
> > ---
> >  drivers/usb/misc/apple-mfi-fastcharge.c | 17 +++++------------
> >  1 file changed, 5 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/usb/misc/apple-mfi-fastcharge.c b/drivers/usb/misc/apple-mfi-fastcharge.c
> > index 9de0171b5177..de86e389a008 100644
> > --- a/drivers/usb/misc/apple-mfi-fastcharge.c
> > +++ b/drivers/usb/misc/apple-mfi-fastcharge.c
> > @@ -178,16 +178,13 @@ static int mfi_fc_probe(struct usb_device *udev)
> >  {
> >       struct power_supply_config battery_cfg = {};
> >       struct mfi_device *mfi = NULL;
> > -     int err;
> >
> >       if (!mfi_fc_match(udev))
> >               return -ENODEV;
> >
> > -     mfi = kzalloc(sizeof(struct mfi_device), GFP_KERNEL);
> > -     if (!mfi) {
> > -             err = -ENOMEM;
> > -             goto error;
> > -     }
> > +     mfi = devm_kzalloc(&udev->dev, sizeof(*mfi), GFP_KERNEL);
> > +     if (!mfi)
> > +             return -ENOMEM;
> >
> >       battery_cfg.drv_data = mfi;
> >
> > @@ -197,8 +194,7 @@ static int mfi_fc_probe(struct usb_device *udev)
> >                                               &battery_cfg);
> >       if (IS_ERR(mfi->battery)) {
> >               dev_err(&udev->dev, "Can't register battery\n");
> > -             err = PTR_ERR(mfi->battery);
> > -             goto error;
> > +             return PTR_ERR(mfi->battery);
> >       }
> >
> >       mfi->udev = usb_get_dev(udev);
> > @@ -206,9 +202,6 @@ static int mfi_fc_probe(struct usb_device *udev)
> >
> >       return 0;
> >
> > -error:
> > -     kfree(mfi);
> > -     return err;
> >  }
> >
> >  static void mfi_fc_disconnect(struct usb_device *udev)
> > @@ -220,7 +213,7 @@ static void mfi_fc_disconnect(struct usb_device *udev)
> >               power_supply_unregister(mfi->battery);
> >       dev_set_drvdata(&udev->dev, NULL);
> >       usb_put_dev(mfi->udev);
> > -     kfree(mfi);
> > +     devm_kfree(&udev->dev, mfi);
>
> Are you sure about this?
I think so, as the probe will allocate again that struct, the
disconnect should free the previous one.

>
> And what's wrong with the existing code?  Using the devm_*() variants
> seems like a "cleanup", but it's not always the case.
I don't know what's wrong, but I will figure out.
>
> thanks,
>
> greg k-h

Thanks
Lucas