Commit dbecef68 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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tracing: Add tracer_tracing_disable/enable() functions 



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: default avatarDouglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/20250505212235.210330010@goodmis.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 1577683a

kernel/trace/trace.c

+33 −0
Original line number Diff line number Diff line
@@ -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

 *

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -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,