tracing: Fix regression of trace_options file setting

The latest change to allow trace options to be set on the command
line also broke the trace_options file.

The zeroing of the last byte of the option name that is echoed into
the trace_option file was removed with the consolidation of some
of the code. The compare between the option and what was written to
the trace_options file fails because the string holding the data
written doesn't terminate with a null character.

A zero needs to be added to the end of the string copied from
user space.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e5125677efa0..1bbfa0446507 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2899,6 +2899,8 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
         if (copy_from_user(&buf, ubuf, cnt))
                 return -EFAULT;
 
+        buf[cnt] = 0;
+
         trace_set_options(buf);
 
         *ppos += cnt;