[Xen-changelog] [xen-4.1-testing] preempt: Disable preemption support for 4.1.

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1299324929 0
# Node ID 51e74954aa8fa9d2777e02b8490e4dd277098149
# Parent  6af8e01d3e4a5b4c6b38c64ceb1cdce897cc8ff2
preempt: Disable preemption support for 4.1.

Preemption support is not needed for 4.1 branch as synchronous yield
(via waitqueues) is not used. Furthermore there are still some
unbalanced rcu_lock/unlock usages on some code paths and the stricter
requirements of the preemption subsystem can cause us to BUG out on
them.

Signed-off-by: Keir Fraser <keir@xxxxxxx>
---


diff -r 6af8e01d3e4a -r 51e74954aa8f xen/include/xen/preempt.h
--- a/xen/include/xen/preempt.h Sat Mar 05 11:25:30 2011 +0000
+++ b/xen/include/xen/preempt.h Sat Mar 05 11:35:29 2011 +0000
@@ -16,6 +16,14 @@
 
 DECLARE_PER_CPU(unsigned int, __preempt_count);
 
+/*
+ * XXX: Preemption support is not needed for 4.1 branch as synchronous
+ * yield (via waitqueues) is not used. Furthermore there are still some
+ * unbalanced rcu_lock/unlock usages on some code paths and the stricter
+ * requirements of the preemption subsystem can cause us to BUG out on them.
+ */
+#if 0
+
 #define preempt_count() (this_cpu(__preempt_count))
 
 #define preempt_disable() do {                  \
@@ -28,6 +36,14 @@
     preempt_count()--;                          \
 } while (0)
 
+#else
+
+#define preempt_count()   0
+#define preempt_disable() ((void)0)
+#define preempt_enable()  ((void)0)
+
+#endif
+
 #define in_atomic() (preempt_count() || in_irq() || !local_irq_is_enabled())
 
 #endif /* __XEN_PREEMPT_H__ */

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