Re: [PATCH v18 09/14] mm/damon: Implement a debugfs interface

[SeongJae Park <sjpark@amazon.com>]

On Mon, 13 Jul 2020 10:41:39 +0200 SeongJae Park <sjpark@amazon.com> wrote:

> From: SeongJae Park <sjpark@amazon.de>
> 
> This commit implements a debugfs interface for DAMON.  It works for the
> virtual address spaces monitoring.
> 
[...]
> +/*
> + * Converts a string into an array of unsigned long integers
> + *
> + * Returns an array of unsigned long integers if the conversion success, or
> + * NULL otherwise.
> + */
> +static int *str_to_pids(const char *str, ssize_t len, ssize_t *nr_pids)
> +{
> +	int *pids;
> +	const int max_nr_pids = 32;
> +	int pid;
> +	int pos = 0, parsed, ret;
> +
> +	*nr_pids = 0;
> +	pids = kmalloc_array(max_nr_pids, sizeof(pid), GFP_KERNEL);
> +	if (!pids)
> +		return NULL;
> +	while (*nr_pids < max_nr_pids && pos < len) {
> +		ret = sscanf(&str[pos], "%d%n", &pid, &parsed);
> +		pos += parsed;
> +		if (ret != 1)
> +			break;
> +		pids[*nr_pids] = pid;
> +		*nr_pids += 1;
> +	}
> +	if (*nr_pids == 0) {
> +		kfree(pids);
> +		pids = NULL;
> +	}

Hmm, this means debugfs users cannot make 'target_ids' empty again.  I will fix
this in the next spin.


Thanks,
SeongJae Park