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Subject[PATCH 6/7] libperF: Add group support to perf_evsel__open
Date
Adding support to set group_fd in perf_evsel__open
call and make it to follow the group setup.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/lib/perf/evsel.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index 3e6638d27c45..9ebf7122d476 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -17,6 +17,7 @@
#include <linux/string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
+#include <asm/bug.h>

void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr,
int idx)
@@ -76,6 +77,25 @@ sys_perf_event_open(struct perf_event_attr *attr,
return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
}

+static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread)
+{
+ struct perf_evsel *leader = evsel->leader;
+ int fd;
+
+ if (evsel == leader)
+ return -1;
+
+ /*
+ * Leader must be already processed/open,
+ * if not it's a bug.
+ */
+ BUG_ON(!leader->fd);
+
+ fd = FD(leader, cpu, thread);
+ BUG_ON(fd == -1);
+ return fd;
+}
+
int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
struct perf_thread_map *threads)
{
@@ -111,11 +131,13 @@ int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,

for (cpu = 0; cpu < cpus->nr; cpu++) {
for (thread = 0; thread < threads->nr; thread++) {
- int fd;
+ int fd, group_fd;
+
+ group_fd = get_group_fd(evsel, cpu, thread);

fd = sys_perf_event_open(&evsel->attr,
threads->map[thread].pid,
- cpus->map[cpu], -1, 0);
+ cpus->map[cpu], group_fd, 0);

if (fd < 0)
return -errno;
--
2.31.1
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