PR10177: init/kill time in sleepy context only

Previously, _stp_init_time and _stp_kill_time were being called from
begin/end/error probes, which will run with preemption disabled.  The
BUG reported on RT kernels showed that cpufreq_unregister_notifier can
end up sleeping, which violates our preemption block.

This patch moves the init/kill into systemtap_module_init/exit, where it
is safe to sleep.  The code maintains a new predicate with the define
STAP_NEED_GETTIMEOFDAY, so we don't still incur any timer overhead if
it's not used.

3 files changed, 26 insertions, 29 deletions

diff --git a/testsuite/buildok/gtod_init.stp b/testsuite/buildok/gtod_init.stp
new file mode 100755
index 00000000..1d76aeab
--- /dev/null
+++ b/testsuite/buildok/gtod_init.stp
@@ -0,0 +1,13 @@
+#! stap -gp4
+
+# check that STAP_NEED_GETTIMEOFDAY is defined with a gettimeofday
+function check() %{
+#ifndef STAP_NEED_GETTIMEOFDAY
+#error "gettimeofday should define STAP_NEED_GETTIMEOFDAY!"
+#endif
+%}
+
+probe begin {
+    check()
+    println(gettimeofday_s())
+}
diff --git a/testsuite/buildok/gtod_noinit.stp b/testsuite/buildok/gtod_noinit.stp
new file mode 100755
index 00000000..94a9dfdc
--- /dev/null
+++ b/testsuite/buildok/gtod_noinit.stp
@@ -0,0 +1,13 @@
+#! stap -gp4
+
+# check that STAP_NEED_GETTIMEOFDAY is NOT defined without a gettimeofday
+function check() %{
+#ifdef STAP_NEED_GETTIMEOFDAY
+#error "STAP_NEED_GETTIMEOFDAY should not be defined!"
+#endif
+%}
+
+probe begin {
+    check()
+    println(get_cycles())
+}
diff --git a/testsuite/systemtap.base/gtod_init.exp b/testsuite/systemtap.base/gtod_init.exp
deleted file mode 100644
index 48616b1f..00000000
--- a/testsuite/systemtap.base/gtod_init.exp
+++ /dev/null
@@ -1,29 +0,0 @@
-# test for checking initialization of the time subsystem
-set test "gtod_init"
-
-# check that init and kill are both present with a gettimeofday
-set time_init 0
-set time_kill 0
-spawn stap -p2 -e {probe begin { println(gettimeofday_s()) }}
-expect {
-	-timeout 120
-	-re {\n_gettimeofday_init:} { incr time_init; exp_continue }
-	-re {\n_gettimeofday_kill:} { incr time_kill; exp_continue }
-	timeout { fail "$test (timeout)" }
-	eof {
-        if {$time_init == 1} { pass "$test (init)" } { fail "$test (init $time_init)" }
-        if {$time_kill == 1} { pass "$test (kill)" } { fail "$test (kill $time_kill)" }
-    }
-}
-wait
-
-# check that init and kill are both NOT present without a gettimeofday
-spawn stap -p2 -e {probe begin { println(get_cycles()) }}
-expect {
-	-timeout 120
-	-re {\n_gettimeofday_init:} { fail "$test (bad init)" }
-	-re {\n_gettimeofday_kill:} { fail "$test (bad kill)" }
-	timeout { fail "$test (timeout)" }
-	eof { pass "$test (no init/kill)" }
-}
-wait