linux-kernel - RE: [RFC PATCH v2 5/7] libperf: Add perf_evsel__check

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Date:   Mon, 11 Apr 2022 08:35:32 +0000
From:   "nakamura.shun@...itsu.com" <nakamura.shun@...itsu.com>
To:     'Jiri Olsa' <olsajiri@...il.com>
CC:     "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>
Subject: RE: [RFC PATCH v2 5/7] libperf: Add perf_evsel__check_overflow()
 functions

Hi jirka

> On Fri, Mar 25, 2022 at 01:38:27PM +0900, Shunsuke Nakamura wrote:
> > Add the following functions:
> >
> >   perf_evsel__check_overflow
> >   perf_evsel__check_overflow_cpu
> >
> > to check for perf events with the file descriptor specified in the
> > argument.
> > These functions can be used in signal handlers to check overflow.
> >
> > Signed-off-by: Shunsuke Nakamura <nakamura.shun@...itsu.com>
> > ---
> >  tools/lib/perf/Documentation/libperf.txt |  3 +++
> >  tools/lib/perf/evsel.c                   | 34
> ++++++++++++++++++++++++
> >  tools/lib/perf/include/perf/evsel.h      |  4 +++
> >  tools/lib/perf/libperf.map               |  2 ++
> >  4 files changed, 43 insertions(+)
> >
> > diff --git a/tools/lib/perf/Documentation/libperf.txt
> > b/tools/lib/perf/Documentation/libperf.txt
> > index 700c1ce15159..4ae8d738b948 100644
> > --- a/tools/lib/perf/Documentation/libperf.txt
> > +++ b/tools/lib/perf/Documentation/libperf.txt
> > @@ -165,6 +165,9 @@ SYNOPSIS
> >                                int cpu_map_idx);
> >    int perf_evsel__period(struct perf_evsel *evsel, int period);
> >    int perf_evsel__period_cpu(struct perf_evsel *evsel, int period,
> > int cpu_map_idx);
> > +  int perf_evsel__check_overflow(struct perf_evsel *evsel, int
> > + sig_fd, bool *overflow);  int perf_evsel__check_overflow_cpu(struct
> perf_evsel *evsel, int cpu_map_idx,
> > +                                     int sig_fd, bool *overflow);
> 
> should this be more like:
> 
>   perf_evsel__has_fd(struct perf_evsel *evsel, int fd)
> 
I'll fix it.


> also why do we need to export *_cpu version for this?
> I don't see it used in the test
> 
Sorry, not necessary.
I'll fix it.

> >    struct perf_cpu_map *perf_evsel__cpus(struct perf_evsel *evsel);
> >    struct perf_thread_map *perf_evsel__threads(struct perf_evsel *evsel);
> >    struct perf_event_attr *perf_evsel__attr(struct perf_evsel *evsel);
> > diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c index
> > db9b7274feb5..6ff3cf692df3 100644
> > --- a/tools/lib/perf/evsel.c
> > +++ b/tools/lib/perf/evsel.c
> > @@ -616,3 +616,37 @@ int perf_evsel__open_opts(struct perf_evsel
> > *evsel, struct perf_cpu_map *cpus,
> >
> >  	return err;
> >  }
> > +
> > +int perf_evsel__check_overflow_cpu(struct perf_evsel *evsel, int
> cpu_map_idx,
> > +				   int sig_fd, bool *overflow)
> > +{
> > +	int thread;
> > +	int *fd;
> > +	int err = 0;
> > +
> > +	if (!overflow)
> > +		return -EINVAL;
> > +
> > +	*overflow = false;
> > +
> > +	for (thread = 0; thread < xyarray__max_y(evsel->fd) && !err; ++thread)
> {
> > +		fd = FD(evsel, cpu_map_idx, thread);
> > +		if (sig_fd <= 0 || !fd || *fd < 0)
> > +			err = -EINVAL;
> 
> sig_fd check should be before the loop
> 
I'll fix it.


Best Regards
Shunsuke