From 79eb6a126211dc1cbb20f16f67bad69afa2f9703 Mon Sep 17 00:00:00 2001
From: Robert Love <rml@tech9.net>
Date: Tue, 21 May 2002 03:21:43 -0700
Subject: [PATCH] get/put_cpu methods

This implements a get_cpu() and matching put_cpu() to safely hand out
the current CPU to avoid preempt races.  Andrew and I have been bitching
about the need for such a method.

I also went ahead and replaced an example of current explicit
preempt-off with the new methods, as a case in point.
---
 include/linux/smp.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 85c6273694c9..b61435d369c8 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -96,5 +96,9 @@ static inline void smp_send_reschedule_all(void) { }
 #define per_cpu(var, cpu)			var
 #define this_cpu(var)				var
 
-#endif
-#endif
+#endif /* !SMP */
+
+#define get_cpu()	({ preempt_disable(); smp_processor_id(); })
+#define put_cpu()	preempt_enable()
+
+#endif /* __LINUX_SMP_H */
-- 
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