linux-kernel - Re: [PATCH v3 1/2] HID: i2c-hid: Use devm to allocate i2c

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Date:   Fri, 22 Jun 2018 09:16:28 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Jiri Kosina <jikos@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Dmitry Torokhov <dtor@...omium.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH v3 1/2] HID: i2c-hid: Use devm to allocate i2c_hid struct

On Fri, Jun 22, 2018 at 4:27 AM, Stephen Boyd <swboyd@...omium.org> wrote:
> Use devm here to save some lines and prepare for bulk regulator usage in
> this driver. Otherwise, when we devm bulk get regulators we'll free the
> containing i2c_hid structure and try to put regulator pointers from
> freed memory.
>
> Cc: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: Dmitry Torokhov <dtor@...omium.org>
> Cc: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  drivers/hid/i2c-hid/i2c-hid.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index c1652bb7bd15..c7d6738dc524 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -1002,18 +1002,18 @@ static int i2c_hid_probe(struct i2c_client *client,
>                 return client->irq;
>         }
>
> -       ihid = kzalloc(sizeof(struct i2c_hid), GFP_KERNEL);
> +       ihid = devm_kzalloc(&client->dev, sizeof(*ihid), GFP_KERNEL);

IIRC, I never made the switch towards devm for i2c_hid because at the
time there was a "all or nothing" rule regarding devm.
But given that the regulator already has a devm inside, I think we are
screwed here and we should probably try to devm-ize the module.

I seem to remember that someone posted a devm version of
hid_allocate_device/hid-add_device, but I don't think this ever went
upstream (because no use).

Otherwise, for the series:
Acked-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

Cheers,
Benjamin



>         if (!ihid)
>                 return -ENOMEM;
>
>         if (client->dev.of_node) {
>                 ret = i2c_hid_of_probe(client, &ihid->pdata);
>                 if (ret)
> -                       goto err;
> +                       return ret;
>         } else if (!platform_data) {
>                 ret = i2c_hid_acpi_pdata(client, &ihid->pdata);
>                 if (ret)
> -                       goto err;
> +                       return ret;
>         } else {
>                 ihid->pdata = *platform_data;
>         }
> @@ -1126,7 +1126,6 @@ static int i2c_hid_probe(struct i2c_client *client,
>
>  err:
>         i2c_hid_free_buffers(ihid);
> -       kfree(ihid);
>         return ret;
>  }
>
> @@ -1150,8 +1149,6 @@ static int i2c_hid_remove(struct i2c_client *client)
>
>         regulator_disable(ihid->pdata.supply);
>
> -       kfree(ihid);
> -
>         return 0;
>  }
>
> --
> Sent by a computer through tubes
>