linux-kernel - [PATCH] trace: make ftrace likely counters atomic

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Message-ID: <20251223203715.10954-1-khaled.saleh.req@gmail.com>
Date: Tue, 23 Dec 2025 22:37:14 +0200
From: Khaled Saleh <khaled.saleh.req@...il.com>
To: rostedt@...dmis.org
Cc: mhiramat@...nel.org,
	mathieu.desnoyers@...icios.com,
	linux-kernel@...r.kernel.org,
	Khaled Saleh <khaled.saleh.req@...il.com>
Subject: [PATCH] trace: make ftrace likely counters atomic

The correct and incorrect counters in ftrace_likely_update() are
updated without synchronization and may race on SMP systems.

Convert them to atomic counters to address the existing FIXME
without changing behavior.

Signed-off-by: Khaled Saleh <khaled.saleh.req@...il.com>
---
 kernel/trace/trace_branch.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 6809b370e991..31a144fa975f 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -215,10 +215,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	trace_likely_condition(f, val, expect);
 
 	/* FIXME: Make this atomic! */
-	if (val == expect)
-		f->data.correct++;
-	else
-		f->data.incorrect++;
+	if (val == expect) {
+		atomic_long_inc(&f->data.correct);
+	} else {
+	atomic_long_inc(&f->data.incorrect);
+	}
 
 	user_access_restore(flags);
 }
-- 
2.43.0