lkml.org 
[lkml]   [2011]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] tracing - trace lost events properly
Date
Add proper handling of lost event trace, allowing callers
to get correct trace buffer info.

- returning TRACE_TYPE_PARTIAL_LINE, in case we dont fit into
the trace_seq buffer
- added WARN_ON to make sure we don't miss incorrect trace_seq
handling

wbr,
jirka


Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
kernel/trace/trace.c | 14 +++++++++++---
1 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9541c27..20d84f8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2013,9 +2013,10 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;

- if (iter->lost_events)
- trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
- iter->cpu, iter->lost_events);
+ if (iter->lost_events &&
+ !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
+ iter->cpu, iter->lost_events))
+ return TRACE_TYPE_PARTIAL_LINE;

if (iter->trace && iter->trace->print_line) {
ret = iter->trace->print_line(iter);
@@ -3229,6 +3230,13 @@ waitagain:

if (iter->seq.len >= cnt)
break;
+
+ /*
+ * Setting the full flag means we reached the trace_seq buffer
+ * size and we should leave by partial output condition above.
+ * One of the trace_seq_* functions is not used properly.
+ */
+ WARN_ON(iter->seq.full);
}
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
--
1.7.1


\
 
 \ /
  Last update: 2011-03-13 00:03    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site