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x86, mmiotrace: fix buffer overrun detection 

Impact: fix mmiotrace overrun tracing

When ftrace framework moved to use the ring buffer facility, the buffer
overrun detection was broken after 2.6.27 by commit

| commit 3928a8a2d9
| Author: Steven Rostedt <rostedt@goodmis.org>
| Date:   Mon Sep 29 23:02:41 2008 -0400
|
|     ftrace: make work with new ring buffer
|
|     This patch ports ftrace over to the new ring buffer.

The detection is now fixed by using the ring buffer API.

When mmiotrace detects a buffer overrun, it will report the number of
lost events. People reading an mmiotrace log must know if something was
missed, otherwise the data may not make sense.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Pekka Paalanen 2008-11-23 21:24:30 +02:00 committed by Ingo Molnar
parent 522a110b42
commit 7ee1768ddb
1 changed files with 7 additions and 9 deletions
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16
kernel/trace/trace_mmiotrace.c
View File

@ -18,12 +18,14 @@ struct header_iter {
static struct trace_array *mmio_trace_array;
static bool overrun_detected;
static unsigned long prev_overruns;
static void mmio_reset_data(struct trace_array *tr)
{
int cpu;
overrun_detected = false;
prev_overruns = 0;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
@ -128,16 +130,12 @@ static void mmio_close(struct trace_iterator *iter)
static unsigned long count_overruns(struct trace_iterator *iter)
{
int cpu;
unsigned long cnt = 0;
/* FIXME: */
#if 0
for_each_online_cpu(cpu) {
cnt += iter->overrun[cpu];
iter->overrun[cpu] = 0;
}
#endif
(void)cpu;
unsigned long over = ring_buffer_overruns(iter->tr->buffer);
if (over > prev_overruns)
cnt = over - prev_overruns;
prev_overruns = over;
return cnt;
}