[PATCH RFC 1/7] tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()

While ftrace_set_clr_event() modifies its input buffer during parsing,
before returning to the caller the buffer is supposed to be restored
to its original state.

This works correctly for the colon between the subsystem and event
but not the colon at the beginning of :mod:.

Restore the colon, so the :mod: trailer is not stripped after
ftrace_set_clr_event().

Fixes: 4c86bc531e60 ("tracing: Add :mod: command to enabled module events")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <redacted>
---
 kernel/trace/trace_events.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c46e623e7e0d..6aa32c492280 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c

@@ -1460,6 +1460,8 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
 	/* Put back the colon to allow this to be called again */
 	if (buf)
 		*(buf - 1) = ':';
+	if (mod)
+		*(mod - 5) = ':';
 
 	return ret;
 }

-- 
2.55.0