linux-kernel - [for-linus][PATCH 4/5] samples/trace_printk: Wait for IRQ work to finish

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Date:   Sat, 21 Dec 2019 16:11:10 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable@...r.kernel.org, Sven Schnelle <svens@...ux.ibm.com>
Subject: [for-linus][PATCH 4/5] samples/trace_printk: Wait for IRQ work to finish

From: Sven Schnelle <svens@...ux.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.ibm.com

Cc: stable@...r.kernel.org
Fixes: af2a0750f3749 ("selftests/ftrace: Improve kprobe on module testcase to load/unload module")
Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.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");
-- 
2.24.0