tracing: make trace pipe recognize latency format flag

The trace_pipe did not recognize the latency format flag and would produce
different output than the trace file. The problem was partly due that
the trace flags in the iterator was not set as well as the trace_pipe
zeros out part of the iterator (including the flags) to be able to use
the same routines as the trace file. trace_flags of the iterator should
not cause any problems when not zeroed out by for trace_pipe.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a3a8a87d7e91..cae34c69752f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2826,6 +2826,9 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
         /* trace pipe does not show start of buffer */
         cpumask_setall(iter->started);
 
+        if (trace_flags & TRACE_ITER_LATENCY_FMT)
+                iter->iter_flags |= TRACE_FILE_LAT_FMT;
+
         iter->cpu_file = cpu_file;
         iter->tr = &global_trace;
         mutex_init(&iter->mutex);