linux-kernel - Re: [PATCH v3 14/23] platform/chrome: don't use devm variants for `din` and `dout`

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Date:   Wed, 8 Jun 2022 09:17:12 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Tzung-Bi Shih <tzungbi@...nel.org>
Cc:     Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        "open list:CHROME HARDWARE PLATFORM SUPPORT" 
        <chrome-platform@...ts.linux.dev>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 14/23] platform/chrome: don't use devm variants for
 `din` and `dout`

On Wed, Jun 8, 2022 at 4:08 AM Tzung-Bi Shih <tzungbi@...nel.org> wrote:
>
> Don't use devm variants because the two buffers could be re-allocated
> multiple times during runtime.  Their life cycles aren't quite aligned
> to the device's.
>
> Normally, free the memory if any when the ec_dev gets unregistered in
> cros_ec_unregister().
>
> No need to free memory if kmalloc() fails.  They will be freed
> eventually in either of the following:
> - Error handling path in cros_ec_register().
> - In cros_ec_unregister().
> - Next kmalloc() in cros_ec_query_all().
>
> Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
> Changes from v2:
> - Don't use realloc.
>
> Changes from v1:
> - Don't use devm.
> - Free in cros_ec_unregister().
>
>  drivers/platform/chrome/cros_ec.c            |  4 +++
>  drivers/platform/chrome/cros_ec_proto.c      | 29 ++++++++------------
>  drivers/platform/chrome/cros_ec_proto_test.c |  4 +--
>  3 files changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
> index 29d3b544dafb..fb8cb8a73295 100644
> --- a/drivers/platform/chrome/cros_ec.c
> +++ b/drivers/platform/chrome/cros_ec.c
> @@ -285,6 +285,8 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>  exit:
>         platform_device_unregister(ec_dev->ec);
>         platform_device_unregister(ec_dev->pd);
> +       kfree(ec_dev->din);
> +       kfree(ec_dev->dout);
>         return err;
>  }
>  EXPORT_SYMBOL(cros_ec_register);
> @@ -302,6 +304,8 @@ void cros_ec_unregister(struct cros_ec_device *ec_dev)
>         if (ec_dev->pd)
>                 platform_device_unregister(ec_dev->pd);
>         platform_device_unregister(ec_dev->ec);
> +       kfree(ec_dev->din);
> +       kfree(ec_dev->dout);
>  }
>  EXPORT_SYMBOL(cros_ec_unregister);
>
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index 473654f50bca..8a53e989c7e2 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -469,7 +469,6 @@ static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
>   */
>  int cros_ec_query_all(struct cros_ec_device *ec_dev)
>  {
> -       struct device *dev = ec_dev->dev;
>         u32 ver_mask = 0;
>         int ret;
>
> @@ -492,21 +491,18 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
>                 }
>         }
>
> -       devm_kfree(dev, ec_dev->din);
> -       devm_kfree(dev, ec_dev->dout);
> +       kfree(ec_dev->din);
> +       ec_dev->din = NULL;
> +       kfree(ec_dev->dout);
> +       ec_dev->dout = NULL;
>
> -       ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
> -       if (!ec_dev->din) {
> -               ret = -ENOMEM;
> -               goto exit;
> -       }
> +       ec_dev->din = kmalloc(ec_dev->din_size, GFP_KERNEL);
> +       if (!ec_dev->din)
> +               return -ENOMEM;
>
> -       ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
> -       if (!ec_dev->dout) {
> -               devm_kfree(dev, ec_dev->din);
> -               ret = -ENOMEM;
> -               goto exit;
> -       }
> +       ec_dev->dout = kmalloc(ec_dev->dout_size, GFP_KERNEL);
> +       if (!ec_dev->dout)
> +               return -ENOMEM;
>
>         /* Probe if MKBP event is supported */
>         ret = cros_ec_get_host_command_version_mask(ec_dev,
> @@ -555,10 +551,7 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
>                                 "failed to retrieve wake mask: %d\n", ret);
>         }
>
> -       ret = 0;
> -
> -exit:
> -       return ret;
> +       return 0;
>  }
>  EXPORT_SYMBOL(cros_ec_query_all);
>
> diff --git a/drivers/platform/chrome/cros_ec_proto_test.c b/drivers/platform/chrome/cros_ec_proto_test.c
> index 63071af81c94..ec106d0f5648 100644
> --- a/drivers/platform/chrome/cros_ec_proto_test.c
> +++ b/drivers/platform/chrome/cros_ec_proto_test.c
> @@ -180,8 +180,8 @@ static void cros_ec_proto_test_query_all_pretest(struct kunit *test)
>
>         /*
>          * cros_ec_query_all() will free din and dout and allocate them again to fit the usage by
> -        * calling devm_kfree() and devm_kzalloc().  Set them to NULL as they aren't managed by
> -        * ec_dev->dev but allocated statically in struct cros_ec_proto_test_priv
> +        * calling kfree() and kmalloc().  Set them to NULL as they aren't allocated by kmalloc()
> +        * but allocated statically in struct cros_ec_proto_test_priv
>          * (see cros_ec_proto_test_init()).
>          */
>         ec_dev->din = NULL;
> --
> 2.36.1.255.ge46751e96f-goog
>