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

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Date:   Fri, 25 Mar 2022 13:38:27 +0900
From:   Shunsuke Nakamura <nakamura.shun@...itsu.com>
To:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [RFC PATCH v2 5/7] libperf: Add perf_evsel__check_overflow() functions

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);
   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;
+
+		if (sig_fd == *fd)
+			*overflow = true;
+	}
+
+	return err;
+}
+
+int perf_evsel__check_overflow(struct perf_evsel *evsel, int sig_fd, bool *overflow)
+{
+	int cpu_map_idx;
+	int err = 0;
+
+	for (cpu_map_idx = 0; cpu_map_idx < xyarray__max_x(evsel->fd) && !err; cpu_map_idx++)
+		err = perf_evsel__check_overflow_cpu(evsel, cpu_map_idx, sig_fd, overflow);
+	return err;
+}
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index ecf30bc6303f..d686cfbd88a6 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -74,5 +74,9 @@ LIBPERF_API int perf_evsel__open_opts(struct perf_evsel *evsel,
 				      struct perf_cpu_map *cpus,
 				      struct perf_thread_map *threads,
 				      struct perf_evsel_open_opts *opts);
+LIBPERF_API int perf_evsel__check_overflow(struct perf_evsel *evsel, int sig_fd,
+					   bool *overflow);
+LIBPERF_API int perf_evsel__check_overflow_cpu(struct perf_evsel *evsel,
+					       int cpu_map_idx, int sig_fd, bool *overflow);
 
 #endif /* __LIBPERF_EVSEL_H */
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index 534614fbbb26..981eade34237 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -37,6 +37,8 @@ LIBPERF_0.0.1 {
 		perf_evsel__cpus;
 		perf_evsel__threads;
 		perf_evsel__attr;
+		perf_evsel__check_overflow;
+		perf_evsel__check_overflow_cpu;
 		perf_evlist__new;
 		perf_evlist__delete;
 		perf_evlist__open;
-- 
2.25.1