linux-kernel - [PATCH 1/3] tracing: Skip update_last

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Message-ID: <173886112678.496116.16133647703573943563.stgit@devnote2>
Date: Fri,  7 Feb 2025 01:58:46 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	Mark Rutland <mark.rutland@....com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/3] tracing: Skip update_last_data() if it is already updated

From: Masami Hiramatsu (Google) <mhiramat@...nel.org>

If the last boot data is already cleared, there is no reason to update it
again. Skip if the TRACE_ARRAY_FL_LAST_BOOT is cleared.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
 kernel/trace/trace.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 443f2bc5b856..0f010a34de84 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6041,6 +6041,12 @@ static void update_last_data(struct trace_array *tr)
 	if (!(tr->flags & TRACE_ARRAY_FL_BOOT))
 		return;
 
+	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
+		return;
+
+	/* Only if the buffer has previous boot data clear and update it. */
+	tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;
+
 	/* Reset the module list and reload them */
 	if (tr->scratch) {
 		struct trace_scratch *tscratch = tr->scratch;
@@ -6052,9 +6058,6 @@ static void update_last_data(struct trace_array *tr)
 		module_for_each_mod(save_mod, tr);
 	}
 
-	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
-		return;
-
 	/*
 	 * Need to clear all CPU buffers as there cannot be events
 	 * from the previous boot mixed with events with this boot
@@ -6077,7 +6080,6 @@ static void update_last_data(struct trace_array *tr)
 #else
 	tscratch->kaslr_addr = 0;
 #endif
-	tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;
 }
 
 /**