tracing/ftrace: replace none tracer by nop tracer

Replace "none" tracer by the recently created "nop" tracer.
Both are pretty similar except that nop accepts TRACE_PRINT
or TRACE_SPECIAL entries.

And as a consequence, changing the size of the ring buffer now
requires that tracing has already been disabled.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c8c687088b4d..cb2c3fb7dd54 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -369,4 +369,6 @@ enum trace_iterator_flags {
         TRACE_ITER_PRINTK               = 0x400,
 };
 
+extern struct tracer nop_trace;
+
 #endif /* _LINUX_KERNEL_TRACE_H */