A commit in akpm's tree (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(), re-add the irqsave/restore logic
to make the functionality more generally safe.

Cc: Jan Kara <j...@suse.cz>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Jiri Bohac <jbo...@suse.cz>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
 kernel/printk/printk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 82d19e6..bf62f2b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2586,15 +2586,18 @@ void wake_up_klogd(void)
 
 int printk_sched(const char *fmt, ...)
 {
+       unsigned long flags;
        va_list args;
        int r;
 
+       local_irq_save(flags);
        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));
+       local_irq_restore(flags);
 
        return r;
 }
-- 
1.9.1

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