Commit d60da506 authored by Hiraku Toyooka's avatar Hiraku Toyooka Committed by Steven Rostedt
Browse files

tracing: Add a resize function to make one buffer equivalent to another buffer 

Trace buffer size is now per-cpu, so that there are the following two
patterns in resizing of buffers.

  (1) resize per-cpu buffers to same given size
  (2) resize per-cpu buffers to another trace_array's buffer size
      for each CPU (such as preparing the max_tr which is equivalent
      to the global_trace's size)

__tracing_resize_ring_buffer() can be used for (1), and had
implemented (2) inside it for resetting the global_trace to the
original size.

(2) was also implemented in another place. So this patch assembles
them in a new function - resize_buffer_duplicate_size().

Link: http://lkml.kernel.org/r/20121017025616.2627.91226.stgit@falsita



Signed-off-by: default avatarHiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 1c7d6673

kernel/trace/trace.c

+31 −27
Original line number Diff line number Diff line
@@ -3034,6 +3034,31 @@ static void set_buffer_entries(struct trace_array *tr, unsigned long val) 
		tr->data[cpu]->entries = val;

}



/* resize @tr's buffer to the size of @size_tr's entries */

static int resize_buffer_duplicate_size(struct trace_array *tr,

					struct trace_array *size_tr, int cpu_id)

{

	int cpu, ret = 0;



	if (cpu_id == RING_BUFFER_ALL_CPUS) {

		for_each_tracing_cpu(cpu) {

			ret = ring_buffer_resize(tr->buffer,

					size_tr->data[cpu]->entries, cpu);

			if (ret < 0)

				break;

			tr->data[cpu]->entries = size_tr->data[cpu]->entries;

		}

	} else {

		ret = ring_buffer_resize(tr->buffer,

					size_tr->data[cpu_id]->entries, cpu_id);

		if (ret == 0)

			tr->data[cpu_id]->entries =

				size_tr->data[cpu_id]->entries;

	}



	return ret;

}



static int __tracing_resize_ring_buffer(unsigned long size, int cpu)

{

	int ret;
@@ -3058,23 +3083,8 @@ static int __tracing_resize_ring_buffer(unsigned long size, int cpu) 


	ret = ring_buffer_resize(max_tr.buffer, size, cpu);

	if (ret < 0) {

		int r = 0;



		if (cpu == RING_BUFFER_ALL_CPUS) {

			int i;

			for_each_tracing_cpu(i) {

				r = ring_buffer_resize(global_trace.buffer,

						global_trace.data[i]->entries,

						i);

				if (r < 0)

					break;

			}

		} else {

			r = ring_buffer_resize(global_trace.buffer,

						global_trace.data[cpu]->entries,

						cpu);

		}



		int r = resize_buffer_duplicate_size(&global_trace,

						     &global_trace, cpu);

		if (r < 0) {

			/*

			 * AARGH! We are left with different
@@ -3212,17 +3222,11 @@ static int tracing_set_tracer(const char *buf) 


	topts = create_trace_option_files(t);

	if (t->use_max_tr) {

		int cpu;

		/* we need to make per cpu buffer sizes equivalent */

		for_each_tracing_cpu(cpu) {

			ret = ring_buffer_resize(max_tr.buffer,

						global_trace.data[cpu]->entries,

						cpu);

		ret = resize_buffer_duplicate_size(&max_tr, &global_trace,

						   RING_BUFFER_ALL_CPUS);

		if (ret < 0)

			goto out;

			max_tr.data[cpu]->entries =

					global_trace.data[cpu]->entries;

		}

	}



	if (t->init) {

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