linux-kernel - [PATCH 07/12] tracing: Do not use per CPU array

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Message-ID: <20250502205348.972501388@goodmis.org>
Date: Fri, 02 May 2025 16:51:54 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 07/12] tracing: Do not use per CPU array_buffer.data->disabled for cpumask

From: Steven Rostedt <rostedt@...dmis.org>

The per CPU "disabled" value was the original way to disable tracing when
the tracing subsystem was first created. Today, the ring buffer
infrastructure has its own way to disable tracing. In fact, things have
changed so much since 2008 that many things ignore the disable flag.

Do not bother setting the per CPU disabled flag of the array_buffer data
to use to determine what CPUs can write to the buffer and only rely on the
ring buffer code itself to disabled it.

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/trace.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bae32778b292..8cee71683fe3 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5048,7 +5048,6 @@ int tracing_set_cpumask(struct trace_array *tr,
 		 */
 		if (cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
 				!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-			atomic_inc(&per_cpu_ptr(tr->array_buffer.data, cpu)->disabled);
 			ring_buffer_record_disable_cpu(tr->array_buffer.buffer, cpu);
 #ifdef CONFIG_TRACER_MAX_TRACE
 			ring_buffer_record_disable_cpu(tr->max_buffer.buffer, cpu);
@@ -5056,7 +5055,6 @@ int tracing_set_cpumask(struct trace_array *tr,
 		}
 		if (!cpumask_test_cpu(cpu, tr->tracing_cpumask) &&
 				cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-			atomic_dec(&per_cpu_ptr(tr->array_buffer.data, cpu)->disabled);
 			ring_buffer_record_enable_cpu(tr->array_buffer.buffer, cpu);
 #ifdef CONFIG_TRACER_MAX_TRACE
 			ring_buffer_record_enable_cpu(tr->max_buffer.buffer, cpu);
-- 
2.47.2