Re: [PATCH] coresight: cpu-debug: no need to check return value of debugfs_create functions

[Mathieu Poirier <mathieu.poirier@linaro.org>]

Hi Greg,

On Tue, 18 Jun 2019 at 09:52, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.

Looking around in the kernel there is no shortage of instances where
the return value of debugfs functions are checked and the logic
altered based on these values.  But there are also just as many that
don't...  It also seems counter intuitive to ignore the return value
of any function, something that in most case is guaranteed to raise
admonition.

That being said I am sure there is a good reason to support your
position - would you mind expanding a little so that I can follow?

Thanks,
Mathieu

>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/hwtracing/coresight/coresight-cpu-debug.c | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> index e8819d750938..6446ed69ab2f 100644
> --- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
> +++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> @@ -525,23 +525,12 @@ static const struct file_operations debug_func_knob_fops = {
>
>  static int debug_func_init(void)
>  {
> -       struct dentry *file;
>         int ret;
>
>         /* Create debugfs node */
>         debug_debugfs_dir = debugfs_create_dir("coresight_cpu_debug", NULL);
> -       if (!debug_debugfs_dir) {
> -               pr_err("%s: unable to create debugfs directory\n", __func__);
> -               return -ENOMEM;
> -       }
> -
> -       file = debugfs_create_file("enable", 0644, debug_debugfs_dir, NULL,
> -                                  &debug_func_knob_fops);
> -       if (!file) {
> -               pr_err("%s: unable to create enable knob file\n", __func__);
> -               ret = -ENOMEM;
> -               goto err;
> -       }
> +       debugfs_create_file("enable", 0644, debug_debugfs_dir, NULL,
> +                           &debug_func_knob_fops);
>
>         /* Register function to be called for panic */
>         ret = atomic_notifier_chain_register(&panic_notifier_list,
> --
> 2.22.0
>

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