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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 247b0c1fadfc9a04bcd1f5b1e61d53c8b3359700..dc2b8bd9bc1e5a6b238c3267463971606991c92f 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2590,12 +2590,14 @@ 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;
 }