From: Sven Schnelle svens@linux.ibm.com

trace_printk schedules work via irq_work_queue(), but doesn't wait until it was processed. The kprobe_module.tc testcase does:

:;: "Load module again, which means the event1 should be recorded";: modprobe trace-printk grep "event1:" trace

so the grep which checks the trace file might run before the irq work was processed. Fix this by adding a irq_work_sync().

Link: http://lore.kernel.org/linux-trace-devel/20191218074427.96184-3-svens@linux....

Cc: stable@vger.kernel.org Fixes: af2a0750f3749 ("selftests/ftrace: Improve kprobe on module testcase to load/unload module") Signed-off-by: Sven Schnelle svens@linux.ibm.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org --- samples/trace_printk/trace-printk.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c index 7affc3b50b61..cfc159580263 100644 --- a/samples/trace_printk/trace-printk.c +++ b/samples/trace_printk/trace-printk.c @@ -36,6 +36,7 @@ static int __init trace_printk_init(void)

/* Kick off printing in irq context */ irq_work_queue(&irqwork); + irq_work_sync(&irqwork);

trace_printk("This is a %s that will use trace_bprintk()\n", "static string");