Commit 092a3856 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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ring-buffer: Add ring_buffer_record_is_on_cpu() 

Add the function ring_buffer_record_is_on_cpu() that returns true if the
ring buffer for a give CPU is writable and false otherwise.

Also add tracer_tracing_is_on_cpu() to return if the ring buffer for a
given CPU is writeable for a given trace_array.

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>
Link: https://lore.kernel.org/20250505212236.059853898@goodmis.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 969043af

include/linux/ring_buffer.h

+1 −0
Original line number Diff line number Diff line
@@ -192,6 +192,7 @@ void ring_buffer_record_off(struct trace_buffer *buffer); 
void ring_buffer_record_on(struct trace_buffer *buffer);

bool ring_buffer_record_is_on(struct trace_buffer *buffer);

bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);

bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu);

void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);

void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);

kernel/trace/ring_buffer.c

+18 −0
Original line number Diff line number Diff line
@@ -4882,6 +4882,24 @@ bool ring_buffer_record_is_set_on(struct trace_buffer *buffer) 
	return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF);

}



/**

 * ring_buffer_record_is_on_cpu - return true if the ring buffer can write

 * @buffer: The ring buffer to see if write is enabled

 * @cpu: The CPU to test if the ring buffer can write too

 *

 * Returns true if the ring buffer is in a state that it accepts writes

 *   for a particular CPU.

 */

bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu)

{

	struct ring_buffer_per_cpu *cpu_buffer;



	cpu_buffer = buffer->buffers[cpu];



	return ring_buffer_record_is_set_on(buffer) &&

		!atomic_read(&cpu_buffer->record_disabled);

}



/**

 * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer

 * @buffer: The ring buffer to stop writes to.

kernel/trace/trace.h

+15 −0
Original line number Diff line number Diff line
@@ -673,6 +673,21 @@ struct dentry *trace_create_file(const char *name, 
				 void *data,

				 const struct file_operations *fops);





/**

 * tracer_tracing_is_on_cpu - show real state of ring buffer enabled on for a cpu

 * @tr : the trace array to know if ring buffer is enabled

 * @cpu: The cpu buffer to check if enabled

 *

 * Shows real state of the per CPU buffer if it is enabled or not.

 */

static inline bool tracer_tracing_is_on_cpu(struct trace_array *tr, int cpu)

{

	if (tr->array_buffer.buffer)

		return ring_buffer_record_is_on_cpu(tr->array_buffer.buffer, cpu);

	return false;

}



int tracing_init_dentry(void);



struct ring_buffer_event;