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

From: Arnaldo Carvalho de Melo
Date: Mon Apr 20 2015 - 19:06:55 EST


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 âskipnâ:
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
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