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-rw-r--r--kernel/trace/trace_mmiotrace.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 6d2edbdde93..d0f649a2203 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -17,11 +17,13 @@ struct header_iter {
};
static struct trace_array *mmio_trace_array;
+static bool overrun_detected;
static void mmio_reset_data(struct trace_array *tr)
{
int cpu;
+ overrun_detected = false;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
@@ -124,12 +126,34 @@ static void mmio_close(struct trace_iterator *iter)
iter->private = NULL;
}
+static unsigned long count_overruns(struct trace_iterator *iter)
+{
+ int cpu;
+ unsigned long cnt = 0;
+ for_each_online_cpu(cpu) {
+ cnt += iter->overrun[cpu];
+ iter->overrun[cpu] = 0;
+ }
+ return cnt;
+}
+
static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
char __user *ubuf, size_t cnt, loff_t *ppos)
{
ssize_t ret;
struct header_iter *hiter = iter->private;
struct trace_seq *s = &iter->seq;
+ unsigned long n;
+
+ n = count_overruns(iter);
+ if (n) {
+ /* XXX: This is later than where events were lost. */
+ trace_seq_printf(s, "MARK 0.000000 Lost %lu events.\n", n);
+ if (!overrun_detected)
+ pr_warning("mmiotrace has lost events.\n");
+ overrun_detected = true;
+ goto print_out;
+ }
if (!hiter)
return 0;
@@ -142,6 +166,7 @@ static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
iter->private = NULL;
}
+print_out:
ret = trace_seq_to_user(s, ubuf, cnt);
return (ret == -EBUSY) ? 0 : ret;
}