Re: [PATCH v2 1/9] lib: string_helpers: provide kfree_strarray()

Andy Shevchenko
2020-09-28T12:55:50Z

On Mon, Sep 28, 2020 at 12:41:47PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> There's a common pattern of dynamically allocating an array of char
> pointers and then also dynamically allocating each string in this
> array. Provide a helper for freeing such a string array with one call.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
But see below.

> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> include/linux/string_helpers.h | 2 ++
> lib/string_helpers.c | 25 +++++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
> index 86f150c2a6b6..55b25120a1c6 100644
> --- a/include/linux/string_helpers.h
> +++ b/include/linux/string_helpers.h
> @@ -94,4 +94,6 @@ char *kstrdup_quotable(const char *src, gfp_t gfp);
> char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
> char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
>
> +void kfree_strarray(char **str_array, size_t num_str);
> +
> #endif
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
> index 963050c0283e..bfa4c9f3ca0a 100644
> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c
> @@ -649,3 +649,28 @@ char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
> return pathname;
> }
> EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
> +
> +/**
> + * kfree_strarray - free a number of dynamically allocated strings contained
> + * in an array and the array itself
> + *
> + * @str_array: Dynamically allocated array of strings to free. If NULL - the
> + * function does nothing.
> + * @num_str: Number of strings (starting from the beginning of the array) to
> + * free.
> + *
> + * Passing a non-null str_array and num_str == 0 as well as NULL str_array
> + * are valid use-cases.
> + */
> +void kfree_strarray(char **str_array, size_t num_str)

Hmm... I have missed your answer to
str_array -> array
num_str -> n

The rationale behind dropping str is to avoid duplicates in the name of the
function and its parameters. 'array' is harder to avoid, but also possible,
though I leave it to you.

> +{
> + unsigned int i;
> +
> + if (!str_array)
> + return;
> +
> + for (i = 0; i < num_str; i++)
> + kfree(str_array[i]);
> + kfree(str_array);
> +}
> +EXPORT_SYMBOL_GPL(kfree_strarray);
> --
> 2.26.1
>

--
With Best Regards,
Andy Shevchenko