From 3c3ad385a174d5d2490b2f9c6513b588dc8a1ddb Mon Sep 17 00:00:00 2001
From: John Stultz <john.stultz@linaro.org>
Date: Thu, 22 May 2014 10:43:35 +1000
Subject: [PATCH] printk: disable preemption for printk_sched

An earlier change in -mm (printk: remove separate printk_sched
buffers...), removed the printk_sched irqsave/restore lines since it was
safe for current users.  Since we may be expanding usage of
printk_sched(), disable preepmtion for this function to make it more
generally safe to call.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 kernel/printk/printk.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 398142eddbcf..5aba603cf0d8 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2589,12 +2589,14 @@ int printk_sched(const char *fmt, ...)
 	va_list args;
 	int r;
 
+	preempt_disable();
 	va_start(args, fmt);
 	r = vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL, NULL, 0, fmt, args);
 	va_end(args);
 
 	__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
 	irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+	preempt_enable();
 
 	return r;
 }
-- 
2.39.5