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Message-ID: <20231205220011.041220035@goodmis.org>
Date: Tue, 05 Dec 2023 16:52:11 -0500
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>,
stable@...r.kernel.org
Subject: [PATCH v2 3/3] tracing: Disable snapshot buffer when stopping instance tracers
From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
It use to be that only the top level instance had a snapshot buffer (for
latency tracers like wakeup and irqsoff). When stopping a tracer in an
instance would not disable the snapshot buffer. This could have some
unintended consequences if the irqsoff tracer is enabled.
Consolidate the tracing_start/stop() with tracing_start/stop_tr() so that
all instances behave the same. The tracing_start/stop() functions will
just call their respective tracing_start/stop_tr() with the global_array
passed in.
Cc: stable@...r.kernel.org
Fixes: 6d9b3fa5e7f6 ("tracing: Move tracing_max_latency into trace_array")
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
kernel/trace/trace.c | 110 +++++++++++++------------------------------
1 file changed, 34 insertions(+), 76 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e978868b1a22..2492c6c76850 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2360,13 +2360,7 @@ int is_tracing_stopped(void)
return global_trace.stop_count;
}
-/**
- * tracing_start - quick start of the tracer
- *
- * If tracing is enabled but was stopped by tracing_stop,
- * this will start the tracer back up.
- */
-void tracing_start(void)
+static void tracing_start_tr(struct trace_array *tr)
{
struct trace_buffer *buffer;
unsigned long flags;
@@ -2374,119 +2368,83 @@ void tracing_start(void)
if (tracing_disabled)
return;
- raw_spin_lock_irqsave(&global_trace.start_lock, flags);
- if (--global_trace.stop_count) {
- if (global_trace.stop_count < 0) {
+ raw_spin_lock_irqsave(&tr->start_lock, flags);
+ if (--tr->stop_count) {
+ if (WARN_ON_ONCE(tr->stop_count < 0)) {
/* Someone screwed up their debugging */
- WARN_ON_ONCE(1);
- global_trace.stop_count = 0;
+ tr->stop_count = 0;
}
goto out;
}
/* Prevent the buffers from switching */
- arch_spin_lock(&global_trace.max_lock);
+ arch_spin_lock(&tr->max_lock);
- buffer = global_trace.array_buffer.buffer;
+ buffer = tr->array_buffer.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
#ifdef CONFIG_TRACER_MAX_TRACE
- buffer = global_trace.max_buffer.buffer;
+ buffer = tr->max_buffer.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
#endif
- arch_spin_unlock(&global_trace.max_lock);
-
- out:
- raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
-}
-
-static void tracing_start_tr(struct trace_array *tr)
-{
- struct trace_buffer *buffer;
- unsigned long flags;
-
- if (tracing_disabled)
- return;
-
- /* If global, we need to also start the max tracer */
- if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
- return tracing_start();
-
- raw_spin_lock_irqsave(&tr->start_lock, flags);
-
- if (--tr->stop_count) {
- if (tr->stop_count < 0) {
- /* Someone screwed up their debugging */
- WARN_ON_ONCE(1);
- tr->stop_count = 0;
- }
- goto out;
- }
-
- buffer = tr->array_buffer.buffer;
- if (buffer)
- ring_buffer_record_enable(buffer);
+ arch_spin_unlock(&tr->max_lock);
out:
raw_spin_unlock_irqrestore(&tr->start_lock, flags);
}
/**
- * tracing_stop - quick stop of the tracer
+ * tracing_start - quick start of the tracer
*
- * Light weight way to stop tracing. Use in conjunction with
- * tracing_start.
+ * If tracing is enabled but was stopped by tracing_stop,
+ * this will start the tracer back up.
*/
-void tracing_stop(void)
+void tracing_start(void)
+
+{
+ return tracing_start_tr(&global_trace);
+}
+
+static void tracing_stop_tr(struct trace_array *tr)
{
struct trace_buffer *buffer;
unsigned long flags;
- raw_spin_lock_irqsave(&global_trace.start_lock, flags);
- if (global_trace.stop_count++)
+ raw_spin_lock_irqsave(&tr->start_lock, flags);
+ if (tr->stop_count++)
goto out;
/* Prevent the buffers from switching */
- arch_spin_lock(&global_trace.max_lock);
+ arch_spin_lock(&tr->max_lock);
- buffer = global_trace.array_buffer.buffer;
+ buffer = tr->array_buffer.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
#ifdef CONFIG_TRACER_MAX_TRACE
- buffer = global_trace.max_buffer.buffer;
+ buffer = tr->max_buffer.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
#endif
- arch_spin_unlock(&global_trace.max_lock);
+ arch_spin_unlock(&tr->max_lock);
out:
- raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
+ raw_spin_unlock_irqrestore(&tr->start_lock, flags);
}
-static void tracing_stop_tr(struct trace_array *tr)
+/**
+ * tracing_stop - quick stop of the tracer
+ *
+ * Light weight way to stop tracing. Use in conjunction with
+ * tracing_start.
+ */
+void tracing_stop(void)
{
- struct trace_buffer *buffer;
- unsigned long flags;
-
- /* If global, we need to also stop the max tracer */
- if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
- return tracing_stop();
-
- raw_spin_lock_irqsave(&tr->start_lock, flags);
- if (tr->stop_count++)
- goto out;
-
- buffer = tr->array_buffer.buffer;
- if (buffer)
- ring_buffer_record_disable(buffer);
-
- out:
- raw_spin_unlock_irqrestore(&tr->start_lock, flags);
+ return tracing_stop_tr(&global_trace);
}
static int trace_save_cmdline(struct task_struct *tsk)
--
2.42.0
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