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authorLai Jiangshan <laijs@cn.fujitsu.com>2009-07-28 20:17:22 +0800
committerFrederic Weisbecker <fweisbec@gmail.com>2009-07-28 23:17:23 +0200
commit74e7ff8c50b6b022e6ffaa736b16a4dc161d3eaf (patch)
tree5bbe7b9f239f1e7b0a688b521f5dca8b9ea99ef4
parent38ceb592fcac9110c6b3c87ea0a27bff68c43486 (diff)
tracing: Fix missing function_graph events when we splice_read from trace_pipe
About a half events are missing when we splice_read from trace_pipe. They are unexpectedly consumed because we ignore the TRACE_TYPE_NO_CONSUME return value used by the function graph tracer when it needs to consume the events by itself to walk on the ring buffer. The same problem appears with ftrace_dump() Example of an output before this patch: 1) | ktime_get_real() { 1) 2.846 us | read_hpet(); 1) 4.558 us | } 1) 6.195 us | } After this patch: 0) | ktime_get_real() { 0) | getnstimeofday() { 0) 1.960 us | read_hpet(); 0) 3.597 us | } 0) 5.196 us | } The fix also applies on 2.6.30 Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: stable@kernel.org LKML-Reference: <4A6EEC52.90704@cn.fujitsu.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
-rw-r--r--kernel/trace/trace.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8bc8d8afea6..da984ad065a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3085,7 +3085,8 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
break;
}
- trace_consume(iter);
+ if (ret != TRACE_TYPE_NO_CONSUME)
+ trace_consume(iter);
rem -= count;
if (!find_next_entry_inc(iter)) {
rem = 0;
@@ -4233,8 +4234,11 @@ static void __ftrace_dump(bool disable_tracing)
iter.pos = -1;
if (find_next_entry_inc(&iter) != NULL) {
- print_trace_line(&iter);
- trace_consume(&iter);
+ int ret;
+
+ ret = print_trace_line(&iter);
+ if (ret != TRACE_TYPE_NO_CONSUME)
+ trace_consume(&iter);
}
trace_printk_seq(&iter.seq);