sh: Guard against early IPIs in flush_cache_all().

flush_cache_all() gets called in to when we do some early ioremapping.
Unfortunately on SDK7786 the interrupt controller itself requires
ioremapping, leading to a bit of a chicken and egg scenario. For now,
don't bother with IPI crosscalls if there aren't any other CPUs online.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/arch/sh/mm/cache.c b/arch/sh/mm/cache.c
index b8607fa7ae12..0f4095d7ac8b 100644
--- a/arch/sh/mm/cache.c
+++ b/arch/sh/mm/cache.c
@@ -2,7 +2,7 @@
  * arch/sh/mm/cache.c
  *
  * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
- * Copyright (C) 2002 - 2009  Paul Mundt
+ * Copyright (C) 2002 - 2010  Paul Mundt
  *
  * Released under the terms of the GNU GPL v2.0.
  */
@@ -41,8 +41,17 @@ static inline void cacheop_on_each_cpu(void (*func) (void *info), void *info,
                                    int wait)
 {
         preempt_disable();
-        smp_call_function(func, info, wait);
+
+        /*
+         * It's possible that this gets called early on when IRQs are
+         * still disabled due to ioremapping by the boot CPU, so don't
+         * even attempt IPIs unless there are other CPUs online.
+         */
+        if (num_online_cpus() > 1)
+                smp_call_function(func, info, wait);
+
         func(info);
+
         preempt_enable();
 }