diff mbox series

[v2,2/2] perf lock contention: Check tstamp elem creation

Message ID 20231010054617.1901616-2-namhyung@kernel.org
State New
Headers
Series [v2,1/2] perf lock contention: Clear lock addr after use |

Commit Message

Namhyung Kim Oct. 10, 2023, 5:46 a.m. UTC 
  To be more conservative, let's check the return value of
bpf_map_update_elem() for the tstamp map for a task and change
the flag to BPF_NOEXIST so that it cannot update any existing
element.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/bpf_skel/lock_contention.bpf.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index b11179452e19..69d31fd77cd0 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -328,7 +328,11 @@  int contention_begin(u64 *ctx)
 	if (pelem == NULL) {
 		struct tstamp_data zero = {};
 
-		bpf_map_update_elem(&tstamp, &pid, &zero, BPF_ANY);
+		if (bpf_map_update_elem(&tstamp, &pid, &zero, BPF_NOEXIST) < 0) {
+			__sync_fetch_and_add(&task_fail, 1);
+			return 0;
+		}
+
 		pelem = bpf_map_lookup_elem(&tstamp, &pid);
 		if (pelem == NULL) {
 			__sync_fetch_and_add(&task_fail, 1);