Re: [PATCH 03/44] perf tools: Add user events for AUX area tracing

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Apr 09, 2015 at 06:53:43PM +0300, Adrian Hunter escreveu:
> +static int skipn(int fd, off_t n)
> +{
> +	char buf[4096];
> +	ssize_t ret;
> +
> +	while (n > 0) {
> +		ret = read(fd, buf, MIN(n, sizeof(buf)));
> +		if (ret <= 0)
> +			return ret;
> +		n -= ret;
> +	}
> +
> +	return 0;

We have min() in tools/perf/util/include/linux/kernel.h, and that is
what is being used elsewhere in tools/perf/:

[acme@zoo linux]$ find tools/perf/ -name "*.[ch]" | xargs grep '\<min('
| wc -l
20
[acme@zoo linux]$ find tools/perf/ -name "*.[ch]" | xargs grep '\<max('
| wc -l
8
[acme@zoo linux]$

I noticed it tho because of this:

util/session.c: In function ‘skipn’:
util/session.c:279:28: error: comparison between signed and unsigned
integer expressions [-Werror=sign-compare]
   ret = read(fd, buf, MIN(n, sizeof(buf)));
                            ^
util/session.c:279:47: error: signed and unsigned type in conditional
expression [-Werror=sign-compare]
   ret = read(fd, buf, MIN(n, sizeof(buf)));
                                               ^
cc1: all warnings being treated as errors
make[3]: *** [/tmp/build/perf/util/session.o] Error 1
make[3]: *** Waiting for unfinished jobs....

Fixing it to be:

    ret = read(fd, buf, min(n, (off_t)sizeof(buf)));

Ok?

- Arnaldo