linux-kernel - [for-linus][PATCH 3/8] trace/hwlat: Do not wipe the contents of per-cpu thread data

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Message-ID: <20230319164748.290057187@goodmis.org>
Date:   Sun, 19 Mar 2023 12:46:46 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable@...r.kernel.org, Tero Kristo <tero.kristo@...ux.intel.com>,
        Daniel Bristot de Oliveira <bristot@...nel.org>
Subject: [for-linus][PATCH 3/8] trace/hwlat: Do not wipe the contents of per-cpu thread data

From: Tero Kristo <tero.kristo@...ux.intel.com>

Do not wipe the contents of the per-cpu kthread data when starting the
tracer, as this will completely forget about already running instances
and can later start new additional per-cpu threads.

Link: https://lore.kernel.org/all/20230302113654.2984709-1-tero.kristo@linux.intel.com/
Link: https://lkml.kernel.org/r/20230310100451.3948583-2-tero.kristo@linux.intel.com

Cc: stable@...r.kernel.org
Fixes: f46b16520a087 ("trace/hwlat: Implement the per-cpu mode")
Signed-off-by: Tero Kristo <tero.kristo@...ux.intel.com>
Acked-by: Daniel Bristot de Oliveira <bristot@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/trace_hwlat.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index d440ddd5fd8b..edc26dc22c3f 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -584,9 +584,6 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
 	 */
 	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
 
-	for_each_online_cpu(cpu)
-		per_cpu(hwlat_per_cpu_data, cpu).kthread = NULL;
-
 	for_each_cpu(cpu, current_mask) {
 		retval = start_cpu_kthread(cpu);
 		if (retval)
-- 
2.39.1