[for-next][PATCH 10/13] tracing: Allow RCU to run between postponed startup tests

From: Steven Rostedt
Date: Wed May 08 2019 - 16:26:03 EST

From: Anders Roxell <anders.roxell@xxxxxxxxxx>

When building a allmodconfig kernel for arm64 and boot that in qemu,
CONFIG_FTRACE_STARTUP_TEST gets enabled and that takes time so the
watchdog expires and prints out a message like this:
'watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]'
Depending on what the what test gets called from init_trace_selftests()
it stays minutes in the loop.
Rework so that function cond_resched() gets called in the
init_trace_selftests loop.

Link: http://lkml.kernel.org/r/20181130145622.26334-1-anders.roxell@xxxxxxxxxx

Co-developed-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
kernel/trace/trace.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3259019cc66d..4269af5905e4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1722,6 +1722,10 @@ static __init int init_trace_selftests(void)
pr_info("Running postponed tracer tests:\n");

list_for_each_entry_safe(p, n, &postponed_selftests, list) {
+ /* This loop can take minutes when sanitizers are enabled, so
+ * lets make sure we allow RCU processing.
+ */
+ cond_resched();
ret = run_tracer_selftest(p->type);
/* If the test fails, then warn and remove from available_tracers */
if (ret < 0) {