From: Namhyung Kim <namhyung@kernel.org>
Date: Thu, 27 Feb 2025 19:12:23 +0000 (-0800)
Subject: perf ftrace: Use atomic inc to update histogram in BPF
X-Git-Tag: block-6.15-20250403~13^2~63
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=e1cde2d5e92f6728a022754650b9cb1e38358d50;p=linux-block.git

perf ftrace: Use atomic inc to update histogram in BPF

It should use an atomic instruction to update even if the histogram is
keyed by delta as it's also used for stats.

Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/20250227191223.1288473-3-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---

diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c
index ad7054744678..e731a79a753a 100644
--- a/tools/perf/util/bpf_skel/func_latency.bpf.c
+++ b/tools/perf/util/bpf_skel/func_latency.bpf.c
@@ -142,7 +142,7 @@ do_lookup:
 		if (!hist)
 			return 0;
 
-		*hist += 1;
+		__sync_fetch_and_add(hist, 1);
 
 		__sync_fetch_and_add(&total, delta); // always in nsec
 		__sync_fetch_and_add(&count, 1);