[alsa-devel] [patch] ASoC: soc: snprintf() doesn't return negative

Mark Brown broonie at opensource.wolfsonmicro.com
Mon Oct 11 12:40:09 CEST 2010

On Mon, Oct 11, 2010 at 05:54:17AM +0200, Dan Carpenter wrote:
> In user space snprintf() returns negative on errors but the kernel
> version only returns positives.  It could potentially return sizes

I'm not going to apply this.  snprintf() returns a signed type, checking
that the return value is a reasonable thing to do here - at worst we're
wasting a few cycles in code that's nowhere near a hot path, at best
we're robust in the face of a decision to add error reporting to
snprintf() so it's hard to see this change as an improvement.

> larger than the size of the buffer so we should check for that.

> -	if (ret >= 0)
> -		ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
> +	if (ret > PAGE_SIZE)
> +		ret = PAGE_SIZE;
> +
> +	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);

The PAGE_SIZE part of the change has an issue too, the code immediately
preceeding this is:

	list_for_each_entry(codec, &codec_list, list)
		ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s\n",

so it's rather late to be worrying about PAGE_SIZE after the loop.

Please also try to be a bit more thoughtful in your use of
get_maintainers; try to have a look at why people have come up and
consider if it's really sensible to include them.

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