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Date:	Wed, 24 Jul 2013 21:13:01 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>,
	linux-input <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] HID: trivial devm conversion for special hid drivers

On Wed, Jul 24, 2013 at 8:38 PM, Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
> It is safe to use devres allocation within the hid subsystem:
> - the devres release is called _after_ the call to .remove(), meaning
>   that no freed pointers will exists while removing the device
> - if a .probe() fails, devres releases all the allocated ressources
>   before going to the next driver: there will not be ghost ressources
>   attached to a hid device if several drivers are probed.
>
> Given that, we can clean up a little some of the HID drivers. These ones
> are trivial:
> - there is only one kzalloc in the driver
> - the .remove() callback contains only one kfree on top of hid_hw_stop()
> - the error path in the probe is easy enough to be manually checked

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
>  drivers/hid/hid-a4tech.c     | 21 ++++-----------------
>  drivers/hid/hid-apple.c      | 16 +++-------------
>  drivers/hid/hid-magicmouse.c | 17 +++--------------
>  drivers/hid/hid-sony.c       |  9 +++------
>  drivers/hid/hid-zydacron.c   | 19 +++----------------
>  5 files changed, 16 insertions(+), 66 deletions(-)
>
> diff --git a/drivers/hid/hid-a4tech.c b/drivers/hid/hid-a4tech.c
> index 7c5507e..9428ea7 100644
> --- a/drivers/hid/hid-a4tech.c
> +++ b/drivers/hid/hid-a4tech.c
> @@ -90,11 +90,10 @@ static int a4_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         struct a4tech_sc *a4;
>         int ret;
>
> -       a4 = kzalloc(sizeof(*a4), GFP_KERNEL);
> +       a4 = devm_kzalloc(&hdev->dev, sizeof(*a4), GFP_KERNEL);
>         if (a4 == NULL) {
>                 hid_err(hdev, "can't alloc device descriptor\n");
> -               ret = -ENOMEM;
> -               goto err_free;
> +               return -ENOMEM;
>         }
>
>         a4->quirks = id->driver_data;
> @@ -104,27 +103,16 @@ static int a4_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         ret = hid_parse(hdev);
>         if (ret) {
>                 hid_err(hdev, "parse failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
>         if (ret) {
>                 hid_err(hdev, "hw start failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         return 0;
> -err_free:
> -       kfree(a4);
> -       return ret;
> -}
> -
> -static void a4_remove(struct hid_device *hdev)
> -{
> -       struct a4tech_sc *a4 = hid_get_drvdata(hdev);
> -
> -       hid_hw_stop(hdev);
> -       kfree(a4);
>  }
>
>  static const struct hid_device_id a4_devices[] = {
> @@ -144,7 +132,6 @@ static struct hid_driver a4_driver = {
>         .input_mapped = a4_input_mapped,
>         .event = a4_event,
>         .probe = a4_probe,
> -       .remove = a4_remove,
>  };
>  module_hid_driver(a4_driver);
>
> diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
> index c7710b5..881cf7b 100644
> --- a/drivers/hid/hid-apple.c
> +++ b/drivers/hid/hid-apple.c
> @@ -349,7 +349,7 @@ static int apple_probe(struct hid_device *hdev,
>         unsigned int connect_mask = HID_CONNECT_DEFAULT;
>         int ret;
>
> -       asc = kzalloc(sizeof(*asc), GFP_KERNEL);
> +       asc = devm_kzalloc(&hdev->dev, sizeof(*asc), GFP_KERNEL);
>         if (asc == NULL) {
>                 hid_err(hdev, "can't alloc apple descriptor\n");
>                 return -ENOMEM;
> @@ -362,7 +362,7 @@ static int apple_probe(struct hid_device *hdev,
>         ret = hid_parse(hdev);
>         if (ret) {
>                 hid_err(hdev, "parse failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         if (quirks & APPLE_HIDDEV)
> @@ -373,19 +373,10 @@ static int apple_probe(struct hid_device *hdev,
>         ret = hid_hw_start(hdev, connect_mask);
>         if (ret) {
>                 hid_err(hdev, "hw start failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         return 0;
> -err_free:
> -       kfree(asc);
> -       return ret;
> -}
> -
> -static void apple_remove(struct hid_device *hdev)
> -{
> -       hid_hw_stop(hdev);
> -       kfree(hid_get_drvdata(hdev));
>  }
>
>  static const struct hid_device_id apple_devices[] = {
> @@ -551,7 +542,6 @@ static struct hid_driver apple_driver = {
>         .id_table = apple_devices,
>         .report_fixup = apple_report_fixup,
>         .probe = apple_probe,
> -       .remove = apple_remove,
>         .event = apple_event,
>         .input_mapping = apple_input_mapping,
>         .input_mapped = apple_input_mapped,
> diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
> index 5bc3734..d393eb7 100644
> --- a/drivers/hid/hid-magicmouse.c
> +++ b/drivers/hid/hid-magicmouse.c
> @@ -484,7 +484,7 @@ static int magicmouse_probe(struct hid_device *hdev,
>         struct hid_report *report;
>         int ret;
>
> -       msc = kzalloc(sizeof(*msc), GFP_KERNEL);
> +       msc = devm_kzalloc(&hdev->dev, sizeof(*msc), GFP_KERNEL);
>         if (msc == NULL) {
>                 hid_err(hdev, "can't alloc magicmouse descriptor\n");
>                 return -ENOMEM;
> @@ -498,13 +498,13 @@ static int magicmouse_probe(struct hid_device *hdev,
>         ret = hid_parse(hdev);
>         if (ret) {
>                 hid_err(hdev, "magicmouse hid parse failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
>         if (ret) {
>                 hid_err(hdev, "magicmouse hw start failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         if (!msc->input) {
> @@ -548,19 +548,9 @@ static int magicmouse_probe(struct hid_device *hdev,
>         return 0;
>  err_stop_hw:
>         hid_hw_stop(hdev);
> -err_free:
> -       kfree(msc);
>         return ret;
>  }
>
> -static void magicmouse_remove(struct hid_device *hdev)
> -{
> -       struct magicmouse_sc *msc = hid_get_drvdata(hdev);
> -
> -       hid_hw_stop(hdev);
> -       kfree(msc);
> -}
> -
>  static const struct hid_device_id magic_mice[] = {
>         { HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
>                 USB_DEVICE_ID_APPLE_MAGICMOUSE), .driver_data = 0 },
> @@ -574,7 +564,6 @@ static struct hid_driver magicmouse_driver = {
>         .name = "magicmouse",
>         .id_table = magic_mice,
>         .probe = magicmouse_probe,
> -       .remove = magicmouse_remove,
>         .raw_event = magicmouse_raw_event,
>         .input_mapping = magicmouse_input_mapping,
>         .input_configured = magicmouse_input_configured,
> diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
> index 87fbe29..30dbb6b 100644
> --- a/drivers/hid/hid-sony.c
> +++ b/drivers/hid/hid-sony.c
> @@ -624,7 +624,7 @@ static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         struct sony_sc *sc;
>         unsigned int connect_mask = HID_CONNECT_DEFAULT;
>
> -       sc = kzalloc(sizeof(*sc), GFP_KERNEL);
> +       sc = devm_kzalloc(&hdev->dev, sizeof(*sc), GFP_KERNEL);
>         if (sc == NULL) {
>                 hid_err(hdev, "can't alloc sony descriptor\n");
>                 return -ENOMEM;
> @@ -636,7 +636,7 @@ static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         ret = hid_parse(hdev);
>         if (ret) {
>                 hid_err(hdev, "parse failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         if (sc->quirks & VAIO_RDESC_CONSTANT)
> @@ -649,7 +649,7 @@ static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         ret = hid_hw_start(hdev, connect_mask);
>         if (ret) {
>                 hid_err(hdev, "hw start failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         if (sc->quirks & SIXAXIS_CONTROLLER_USB) {
> @@ -669,8 +669,6 @@ static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         return 0;
>  err_stop:
>         hid_hw_stop(hdev);
> -err_free:
> -       kfree(sc);
>         return ret;
>  }
>
> @@ -682,7 +680,6 @@ static void sony_remove(struct hid_device *hdev)
>                 buzz_remove(hdev);
>
>         hid_hw_stop(hdev);
> -       kfree(sc);
>  }
>
>  static const struct hid_device_id sony_devices[] = {
> diff --git a/drivers/hid/hid-zydacron.c b/drivers/hid/hid-zydacron.c
> index e4cddec..1a660bd 100644
> --- a/drivers/hid/hid-zydacron.c
> +++ b/drivers/hid/hid-zydacron.c
> @@ -169,7 +169,7 @@ static int zc_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         int ret;
>         struct zc_device *zc;
>
> -       zc = kzalloc(sizeof(*zc), GFP_KERNEL);
> +       zc = devm_kzalloc(&hdev->dev, sizeof(*zc), GFP_KERNEL);
>         if (zc == NULL) {
>                 hid_err(hdev, "can't alloc descriptor\n");
>                 return -ENOMEM;
> @@ -180,28 +180,16 @@ static int zc_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         ret = hid_parse(hdev);
>         if (ret) {
>                 hid_err(hdev, "parse failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
>         if (ret) {
>                 hid_err(hdev, "hw start failed\n");
> -               goto err_free;
> +               return ret;
>         }
>
>         return 0;
> -err_free:
> -       kfree(zc);
> -
> -       return ret;
> -}
> -
> -static void zc_remove(struct hid_device *hdev)
> -{
> -       struct zc_device *zc = hid_get_drvdata(hdev);
> -
> -       hid_hw_stop(hdev);
> -       kfree(zc);
>  }
>
>  static const struct hid_device_id zc_devices[] = {
> @@ -217,7 +205,6 @@ static struct hid_driver zc_driver = {
>         .input_mapping = zc_input_mapping,
>         .raw_event = zc_raw_event,
>         .probe = zc_probe,
> -       .remove = zc_remove,
>  };
>  module_hid_driver(zc_driver);
>
> --
> 1.8.3.1
>



-- 
With Best Regards,
Andy Shevchenko
--
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