linux-kernel - Re: [PATCH] coresight: use put

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Date:   Mon, 26 Mar 2018 15:46:00 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] coresight: use put_device() instead of kfree()

drivers/hwtracing/coresight/coresight.c
On 18 March 2018 at 01:38, Arvind Yadav <arvind.yadav.cs@...il.com> wrote:
> Never directly free @dev after calling device_register(), even
> if it returned an error. Always use put_device() to give up the
> reference initialized.
>
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
> ---
>  drivers/hwtracing/coresight/coresight.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
> index 389c4ba..132dfbc 100644
> --- a/drivers/hwtracing/coresight/coresight.c
> +++ b/drivers/hwtracing/coresight/coresight.c
> @@ -1026,8 +1026,10 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
>         dev_set_name(&csdev->dev, "%s", desc->pdata->name);
>
>         ret = device_register(&csdev->dev);
> -       if (ret)
> -               goto err_device_register;
> +       if (ret) {
> +               put_device(&csdev->dev);
> +               goto err_kzalloc_csdev;
> +       }
>
>         mutex_lock(&coresight_mutex);
>
> @@ -1038,8 +1040,6 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
>
>         return csdev;
>
> -err_device_register:
> -       kfree(conns);

Apologies for the late reply, I was travelling.

I suggest to simply replace kfree() with put_device() in order to
concentrate the error handling code in the same area and make sure
that memory allocated for @conns and @refcnts is freed.

Thanks,
Mathieu

>  err_kzalloc_conns:
>         kfree(refcnts);
>  err_kzalloc_refcnts:
> --
> 2.7.4
>