ftrace: restore iterator trace in pipe read

The trace iterator is reset in the read. We still need to restore the tracer
that the trace_pipe was opened with.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 4 insertions, 1 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index fd4ecc292005..d141fc98f3a8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2202,6 +2202,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 {
         struct trace_iterator *iter = filp->private_data;
         struct trace_array_cpu *data;
+        struct trace_array *tr = iter->tr;
+        struct tracer *tracer = iter->trace;
         static cpumask_t mask;
         static int start;
         unsigned long flags;
@@ -2274,7 +2276,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                 cnt = PAGE_SIZE - 1;
 
         memset(iter, 0, sizeof(*iter));
-        iter->tr = &global_trace;
+        iter->tr = tr;
+        iter->trace = tracer;
         iter->pos = -1;
 
         /*