ksym_tracer: Fix to allow writing newline to ksym_trace_filter

It used to work, but now doesn't:

 # echo > ksym_filter
 bash: echo: write error: Invalid argument

It's caused by d954fbf0ff6b5fdfb32350e85a2f15d3db976506
("tracing: Fix wrong usage of strstrip in trace_ksyms").

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B3AF1D7.5040400@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 340b6ff193e0..160a8d8b37a2 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -299,8 +299,8 @@ static ssize_t ksym_trace_filter_write(struct file *file,
          * 2: echo 0 > ksym_trace_filter
          * 3: echo "*:---" > ksym_trace_filter
          */
-        if (!buf[0] || !strcmp(buf, "0") ||
-            !strcmp(buf, "*:---")) {
+        if (!input_string[0] || !strcmp(input_string, "0") ||
+            !strcmp(input_string, "*:---")) {
                 __ksym_trace_reset();
                 ret = 0;
                 goto out;