This is a note to let you know that I've just added the patch titled
tracing: Disable snapshot buffer when stopping instance tracers
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-disable-snapshot-buffer-when-stopping-instance-tracers.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b538bf7d0ec11ca49f536dfda742a5f6db90a798 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Date: Tue, 5 Dec 2023 16:52:11 -0500
Subject: tracing: Disable snapshot buffer when stopping instance tracers
From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
commit b538bf7d0ec11ca49f536dfda742a5f6db90a798 upstream.
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.
Link: https://lkml.kernel.org/r/20231205220011.041220035@xxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Fixes: 6d9b3fa5e7f6 ("tracing: Move tracing_max_latency into trace_array")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 110 +++++++++++++++------------------------------------
1 file changed, 34 insertions(+), 76 deletions(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2284,13 +2284,7 @@ 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;
@@ -2298,119 +2292,83 @@ 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)
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-5.15/tracing-fix-a-possible-race-when-disabling-buffered-events.patch
queue-5.15/tracing-fix-incomplete-locking-when-disabling-buffered-events.patch
queue-5.15/tracing-fix-a-warning-when-allocating-buffered-event.patch
queue-5.15/tracing-disable-snapshot-buffer-when-stopping-instance-tracers.patch
queue-5.15/tracing-always-update-snapshot-buffer-size.patch
