don't fail if ftrace_enable is not there
We should still be able to do tracing if the kernel was not compiled
with function tracer. Don't fail on failure to read ftrace_enable.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/trace-cmd.c b/trace-cmd.c
index 22c3df6..77ce277 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -289,17 +289,26 @@
return ret > 0;
}
-static void set_ftrace(int set)
+static int set_ftrace(int set)
{
+ struct stat buf;
+ char *path = "/proc/sys/kernel/ftrace_enabled";
int fd;
char *val = set ? "1" : "0";
- fd = open("/proc/sys/kernel/ftrace_enabled", O_WRONLY);
+ /* if ftace_enable does not exist, simply ignore it */
+ fd = stat(path, &buf);
+ if (fd < 0)
+ return -ENODEV;
+
+ fd = open(path, O_WRONLY);
if (fd < 0)
die ("Can't %s ftrace", set ? "enable" : "disable");
write(fd, val, 1);
close(fd);
+
+ return 0;
}
void run_cmd(int argc, char **argv)
@@ -1101,6 +1110,7 @@
int plug = 0;
int events = 0;
int options = 0;
+ int fset;
int c;
@@ -1201,7 +1211,7 @@
read_tracing_data();
- set_ftrace(!disable);
+ fset = set_ftrace(!disable);
disable_all();
@@ -1224,6 +1234,9 @@
latency = 1;
stop_threads();
}
+ if (fset < 0 && (strcmp(plugin, "function") == 0 ||
+ strcmp(plugin, "function_graph") == 0))
+ die("function tracing not configured on this kernel");
set_plugin(plugin);
}
