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

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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: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Hiraku Toyooka 2012-10-17 11:56:16 +09:00 committed by Steven Rostedt
parent 1c7d667324
commit d60da506cb
1 changed files with 31 additions and 27 deletions
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58
kernel/trace/trace.c
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@ -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);
if (ret < 0)
goto out;
max_tr.data[cpu]->entries =
global_trace.data[cpu]->entries;
}
ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
RING_BUFFER_ALL_CPUS);
if (ret < 0)
goto out;
}
if (t->init) {