linux-kernel - Re: [PATCH v3 1/4] gpio: virtuser: fix missing lookup table cleanups

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Message-ID: <CAMRc=MfwK8o44MYk9pPAkHn6t+wY3=x99Uy88CKgx7nN8x81mw@mail.gmail.com>
Date: Fri, 3 Jan 2025 15:38:46 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Koichiro Den <koichiro.den@...onical.com>
Cc: linux-gpio@...r.kernel.org, linus.walleij@...aro.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] gpio: virtuser: fix missing lookup table cleanups

On Fri, Jan 3, 2025 at 3:18 PM Koichiro Den <koichiro.den@...onical.com> wrote:
>
> When a virtuser device is created via configfs and the probe fails due
> to an incorrect lookup table, the table is not removed. This prevents
> subsequent probe attempts from succeeding, even if the issue is
> corrected, unless the device is released. Additionally, cleanup is also
> needed in the less likely case of platform_device_register_full()
> failure.
>
> Besides, a consistent memory leak in lookup_table->dev_id was spotted
> using kmemleak by toggling the live state between 0 and 1 with a correct
> lookup table.
>
> Introduce gpio_virtuser_remove_lookup_table() as the counterpart to the
> existing gpio_virtuser_make_lookup_table() and call it from all
> necessary points to ensure proper cleanup.
>
> Fixes: 91581c4b3f29 ("gpio: virtuser: new virtual testing driver for the GPIO API")
> Signed-off-by: Koichiro Den <koichiro.den@...onical.com>
> ---
>  drivers/gpio/gpio-virtuser.c | 36 +++++++++++++++++++++++++-----------
>  1 file changed, 25 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpio/gpio-virtuser.c b/drivers/gpio/gpio-virtuser.c
> index 91b6352c957c..e89b1239b635 100644
> --- a/drivers/gpio/gpio-virtuser.c
> +++ b/drivers/gpio/gpio-virtuser.c
> @@ -1439,6 +1439,15 @@ gpio_virtuser_make_lookup_table(struct gpio_virtuser_device *dev)
>         return 0;
>  }
>
> +static void
> +gpio_virtuser_remove_lookup_table(struct gpio_virtuser_device *dev)
> +{
> +       gpiod_remove_lookup_table(dev->lookup_table);
> +       kfree(dev->lookup_table->dev_id);

Ah, this has been here all along as well. :/


> +       kfree(dev->lookup_table);
> +       dev->lookup_table = NULL;
> +}
> +
>  static struct fwnode_handle *
>  gpio_virtuser_make_device_swnode(struct gpio_virtuser_device *dev)
>  {
> @@ -1487,10 +1496,8 @@ gpio_virtuser_device_activate(struct gpio_virtuser_device *dev)
>         pdevinfo.fwnode = swnode;
>
>         ret = gpio_virtuser_make_lookup_table(dev);
> -       if (ret) {
> -               fwnode_remove_software_node(swnode);
> -               return ret;
> -       }
> +       if (ret)
> +               goto err_remove_swnode;
>
>         reinit_completion(&dev->probe_completion);
>         dev->driver_bound = false;
> @@ -1498,23 +1505,31 @@ gpio_virtuser_device_activate(struct gpio_virtuser_device *dev)
>
>         pdev = platform_device_register_full(&pdevinfo);
>         if (IS_ERR(pdev)) {
> +               ret = PTR_ERR(pdev);
>                 bus_unregister_notifier(&platform_bus_type, &dev->bus_notifier);
> -               fwnode_remove_software_node(swnode);
> -               return PTR_ERR(pdev);
> +               goto err_remove_lookup_table;
>         }
>
>         wait_for_completion(&dev->probe_completion);
>         bus_unregister_notifier(&platform_bus_type, &dev->bus_notifier);
>
>         if (!dev->driver_bound) {
> -               platform_device_unregister(pdev);
> -               fwnode_remove_software_node(swnode);
> -               return -ENXIO;
> +               ret = -ENXIO;
> +               goto err_unregister_pdev;
>         }
>
>         dev->pdev = pdev;
>
>         return 0;
> +
> +err_unregister_pdev:
> +       platform_device_unregister(pdev);
> +err_remove_lookup_table:
> +       gpio_virtuser_remove_lookup_table(dev);
> +err_remove_swnode:
> +       fwnode_remove_software_node(swnode);
> +
> +       return ret;
>  }
>
>  static void
> @@ -1526,10 +1541,9 @@ gpio_virtuser_device_deactivate(struct gpio_virtuser_device *dev)
>
>         swnode = dev_fwnode(&dev->pdev->dev);
>         platform_device_unregister(dev->pdev);
> +       gpio_virtuser_remove_lookup_table(dev);

Any reason for moving it earlier?

Bart

>         fwnode_remove_software_node(swnode);
>         dev->pdev = NULL;
> -       gpiod_remove_lookup_table(dev->lookup_table);
> -       kfree(dev->lookup_table);
>  }
>
>  static ssize_t
> --
> 2.43.0
>