tracing/ftrace: fix unexpected -EINVAL when longest tracer name is set
Impact: fix confusing write() -EINVAL when changing the tracer
The following commit d9e540762f5cdd89f24e518ad1fd31142d0b9726 remade
alive the bug which made the set of a new tracer returning -EINVAL if
this is the longest name of tracer. This patch corrects it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dff4bee..80898f4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2655,6 +2655,9 @@
char buf[max_tracer_type_len+1];
int i;
size_t ret;
+ int err;
+
+ ret = cnt;
if (cnt > max_tracer_type_len)
cnt = max_tracer_type_len;
@@ -2668,12 +2671,11 @@
for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
buf[i] = 0;
- ret = tracing_set_tracer(buf);
- if (!ret)
- ret = cnt;
+ err = tracing_set_tracer(buf);
+ if (err)
+ return err;
- if (ret > 0)
- filp->f_pos += ret;
+ filp->f_pos += ret;
return ret;
}