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tracing: Add tracer_tracing_disable/enable() functions

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Allow a tracer to disable writing to its buffer for a temporary amount of
time and re-enable it.

The tracer_tracing_disable() will disable writing to the trace array
buffer, and requires a tracer_tracing_enable() to re-enable it.

The difference between tracer_tracing_disable() and tracer_tracing_off()
is that the disable version can nest, and requires as many enable() calls
as disable() calls to re-enable the buffer. Where as the off() function
can be called multiple times and only requires a singe tracer_tracing_on()
to re-enable the buffer.

Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daniel Thompson <danielt@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/20250505212235.210330010@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-05-05 17:21:08 -04:00 committed by Steven Rostedt (Google)
parent 1577683a92
commit dbecef68ad
2 changed files with 35 additions and 0 deletions
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33
kernel/trace/trace.c
View File

@ -1582,6 +1582,39 @@ void tracer_tracing_off(struct trace_array *tr)
smp_wmb();
}
/**
* tracer_tracing_disable() - temporary disable the buffer from write
* @tr: The trace array to disable its buffer for
*
* Expects trace_tracing_enable() to re-enable tracing.
* The difference between this and tracer_tracing_off() is that this
* is a counter and can nest, whereas, tracer_tracing_off() can
* be called multiple times and a single trace_tracing_on() will
* enable it.
*/
void tracer_tracing_disable(struct trace_array *tr)
{
if (WARN_ON_ONCE(!tr->array_buffer.buffer))
return;
ring_buffer_record_disable(tr->array_buffer.buffer);
}
/**
* tracer_tracing_enable() - counter part of tracer_tracing_disable()
* @tr: The trace array that had tracer_tracincg_disable() called on it
*
* This is called after tracer_tracing_disable() has been called on @tr,
* when it's safe to re-enable tracing.
*/
void tracer_tracing_enable(struct trace_array *tr)
{
if (WARN_ON_ONCE(!tr->array_buffer.buffer))
return;
ring_buffer_record_enable(tr->array_buffer.buffer);
}
/**
* tracing_off - turn off tracing buffers
*

2
kernel/trace/trace.h
View File

@ -665,6 +665,8 @@ bool tracing_is_disabled(void);
bool tracer_tracing_is_on(struct trace_array *tr);
void tracer_tracing_on(struct trace_array *tr);
void tracer_tracing_off(struct trace_array *tr);
void tracer_tracing_disable(struct trace_array *tr);
void tracer_tracing_enable(struct trace_array *tr);
struct dentry *trace_create_file(const char *name,
umode_t mode,
struct dentry *parent,