Commit f5eb5588 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
Browse files

ring-buffer: Do not use schedule_work_on() for current CPU 



The ring buffer updates when done while the ring buffer is active,
needs to be completed on the CPU that is used for the ring buffer
per_cpu buffer. To accomplish this, schedule_work_on() is used to
schedule work on the given CPU.

Now there's no reason to use schedule_work_on() if the process
doing the update happens to be on the CPU that it is processing.
It has already filled the requirement. Instead, just do the work
and continue.

This is needed for tracing_snapshot_alloc() where it may be called
really early in boot, where the work queues have not been set up yet.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent ad909e21

kernel/trace/ring_buffer.c

+27 −6
Original line number Diff line number Diff line
@@ -1679,11 +1679,22 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, 
			if (!cpu_buffer->nr_pages_to_update)

				continue;



			if (cpu_online(cpu))

			/* The update must run on the CPU that is being updated. */

			preempt_disable();

			if (cpu == smp_processor_id() || !cpu_online(cpu)) {

				rb_update_pages(cpu_buffer);

				cpu_buffer->nr_pages_to_update = 0;

			} else {

				/*

				 * Can not disable preemption for schedule_work_on()

				 * on PREEMPT_RT.

				 */

				preempt_enable();

				schedule_work_on(cpu,

						&cpu_buffer->update_pages_work);

			else

				rb_update_pages(cpu_buffer);

				preempt_disable();

			}

			preempt_enable();

		}



		/* wait for all the updates to complete */
@@ -1721,12 +1732,22 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, 


		get_online_cpus();



		if (cpu_online(cpu_id)) {

		preempt_disable();

		/* The update must run on the CPU that is being updated. */

		if (cpu_id == smp_processor_id() || !cpu_online(cpu_id))

			rb_update_pages(cpu_buffer);

		else {

			/*

			 * Can not disable preemption for schedule_work_on()

			 * on PREEMPT_RT.

			 */

			preempt_enable();

			schedule_work_on(cpu_id,

					 &cpu_buffer->update_pages_work);

			wait_for_completion(&cpu_buffer->update_done);

		} else

			rb_update_pages(cpu_buffer);

			preempt_disable();

		}

		preempt_enable();



		cpu_buffer->nr_pages_to_update = 0;

		put_online_cpus();

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