tracing: make testing syscall events a separate configuration

Parag noticed that the number of event tests has increased tremendously:

grep "Testing event" dmesg.31rc9 |wc -l
100

grep "Testing event" dmesg.31git |wc -l
1172

This is due to the testing of every syscall event when ftrace self
test is enabled. This adds a bit more time to kernel boot up and can
affect development by slowing down the time it takes between reboots.

This option makes the testing of the syscall events into a separate
config, to still be able to test most of ftrace internals at boot up
but not have to wait for all the syscall events to be tested.

The syscall event testing only tests the enabling and disabling of
the trace point, since the syscalls are not executed. What really needs
to be done is to somehow have a userspace tool test the syscall tracepoints
as well.

Reported-by: Parag Warudkar <parag.lkml@gmail.com>
LKML-Reference: <f7848160909130815l3e768a30n3b28808bbe5c254b@mail.gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0fa8f9faa61c..787f0fb0994e 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1326,6 +1326,18 @@ static __init void event_trace_self_tests(void)
                 if (!call->regfunc)
                         continue;
 
+/*
+ * Testing syscall events here is pretty useless, but
+ * we still do it if configured. But this is time consuming.
+ * What we really need is a user thread to perform the
+ * syscalls as we test.
+ */
+#ifndef CONFIG_EVENT_TRACE_TEST_SYSCALLS
+                if (call->system &&
+                    strcmp(call->system, "syscalls") == 0)
+                        continue;
+#endif
+
                 pr_info("Testing event %s: ", call->name);
 
                 /*