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

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Date:   Fri, 25 Feb 2022 19:31:12 +0900
From:   Shunsuke <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,
        Shunsuke Nakamura <nakamura.shun@...itsu.com>
Subject: [RFC PATCH 5/7] libperf: Add perf_evsel__check_fd() functions

From: Shunsuke Nakamura <nakamura.shun@...itsu.com>

Add the following functions:

  perf_evsel__check_fd()
  perf_evsel__check_fd_cpu()

to check for perf events with the file descriptor specified in the
argument.
These functions can be used in signal handlers to detect overflow.

Signed-off-by: Shunsuke Nakamura <nakamura.shun@...itsu.com>
---
 tools/lib/perf/Documentation/libperf.txt |  2 ++
 tools/lib/perf/evsel.c                   | 27 ++++++++++++++++++++++++
 tools/lib/perf/include/perf/evsel.h      |  2 ++
 tools/lib/perf/libperf.map               |  2 ++
 4 files changed, 33 insertions(+)

diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
index d0aa57c6ca97..d3a1a9e77262 100644
--- a/tools/lib/perf/Documentation/libperf.txt
+++ b/tools/lib/perf/Documentation/libperf.txt
@@ -155,6 +155,8 @@ SYNOPSIS
                              struct sigaction *sig);
   int perf_evsel__set_signal_cpu(struct perf_evsel *evsel, int owner_type, unsigned int signal,
                                  struct sigaction *sig, int cpu_map_idx);
+  int perf_evsel__check_fd(struct perf_evsel *evsel, int sig_fd);
+  int perf_evsel__check_fd_cpu(struct perf_evsel *evsel, int cpu_map_idx, int sig_fd);
   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 991ab04112b1..0c626f846980 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -542,6 +542,33 @@ int perf_evsel__set_signal(struct perf_evsel *evsel, int owner_type, unsigned in
 	return err;
 }
 
+int perf_evsel__check_fd_cpu(struct perf_evsel *evsel, int cpu_map_idx, int sig_fd)
+{
+	int thread;
+	int *fd;
+
+	for (thread = 0; thread < xyarray__max_y(evsel->fd); ++thread) {
+		fd = FD(evsel, cpu_map_idx, thread);
+		if (sig_fd <= 0 || !fd || *fd < 0)
+			return -1;
+
+		if (sig_fd == *fd)
+			return 0;
+	}
+
+	return -1;
+}
+
+int perf_evsel__check_fd(struct perf_evsel *evsel, int sig_fd)
+{
+	int i;
+	int err = 0;
+
+	for (i = 0; i < xyarray__max_x(evsel->fd); i++)
+		err = perf_evsel__check_fd_cpu(evsel, i, sig_fd);
+	return err;
+}
+
 int perf_evsel__apply_filter(struct perf_evsel *evsel, const char *filter)
 {
 	int err = 0, i;
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index 15768fc91910..5d4b4912fec9 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -49,6 +49,8 @@ LIBPERF_API int perf_evsel__set_signal(struct perf_evsel *evsel, int owner_type,
 LIBPERF_API int perf_evsel__set_signal_cpu(struct perf_evsel *evsel, int owner_type,
 					   unsigned int signal, struct sigaction *sig,
 					   int cpu_map_idx);
+LIBPERF_API int perf_evsel__check_fd(struct perf_evsel *evsel, int sig_fd);
+LIBPERF_API int perf_evsel__check_fd_cpu(struct perf_evsel *evsel, int cpu_map_idx, int sig_fd);
 LIBPERF_API struct perf_cpu_map *perf_evsel__cpus(struct perf_evsel *evsel);
 LIBPERF_API struct perf_thread_map *perf_evsel__threads(struct perf_evsel *evsel);
 LIBPERF_API struct perf_event_attr *perf_evsel__attr(struct perf_evsel *evsel);
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index 5e04fe2b611c..edd60bc69822 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -34,6 +34,8 @@ LIBPERF_0.0.1 {
 		perf_evsel__period_cpu;
 		perf_evsel__set_signal;
 		perf_evsel__set_signal_cpu;
+		perf_evsel__check_fd;
+		perf_evsel__check_fd_cpu;
 		perf_evsel__cpus;
 		perf_evsel__threads;
 		perf_evsel__attr;
-- 
2.31.1