Provide support for this_cpu_cmpxchg.

Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
 include/linux/percpu.h |   99 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

Index: linux-2.6/include/linux/percpu.h
===================================================================
--- linux-2.6.orig/include/linux/percpu.h	2009-12-18 15:17:05.000000000 -0600
+++ linux-2.6/include/linux/percpu.h	2009-12-18 15:33:12.000000000 -0600
@@ -443,6 +443,62 @@ do {									\
 # define this_cpu_xor(pcp, val)		__pcpu_size_call(this_cpu_or_, (pcp), (val))
 #endif
 
+static inline unsigned long __this_cpu_cmpxchg_generic(volatile void *pptr,
+		unsigned long old, unsigned long new, int size)
+{
+	unsigned long prev;
+	volatile void * ptr = __this_cpu_ptr(pptr);
+
+	switch (size) {
+	case 1: prev = *(u8 *)ptr;
+		if (prev == old)
+			*(u8 *)ptr = (u8)new;
+		break;
+	case 2: prev = *(u16 *)ptr;
+		if (prev == old)
+			*(u16 *)ptr = (u16)new;
+		break;
+	case 4: prev = *(u32 *)ptr;
+		if (prev == old)
+			*(u32 *)ptr = (u32)new;
+		break;
+	case 8: prev = *(u64 *)ptr;
+		if (prev == old)
+			*(u64 *)ptr = (u64)new;
+		break;
+	default:
+		__bad_size_call_parameter();
+	}
+	return prev;
+}
+
+static inline unsigned long this_cpu_cmpxchg_generic(volatile void *ptr,
+		unsigned long old, unsigned long new, int size)
+{
+	unsigned long prev;
+
+	preempt_disable();
+	prev = __this_cpu_cmpxchg_generic(ptr, old, new, size);
+	preempt_enable();
+	return prev;
+}
+
+#ifndef this_cpu_cmpxchg
+# ifndef this_cpu_cmpxchg_1
+#  define this_cpu_cmpxchg_1(pcp, old, new) this_cpu_cmpxchg_generic((pcp), (old), (new), 1)
+# endif
+# ifndef this_cpu_cmpxchg_2
+#  define this_cpu_cmpxchg_2(pcp, old, new) this_cpu_cmpxchg_generic((pcp), (old), (new), 2)
+# endif
+# ifndef this_cpu_cmpxchg_4
+#  define this_cpu_cmpxchg_4(pcp, old, new) this_cpu_cmpxchg_generic((pcp), (old), (new), 4)
+# endif
+# ifndef this_cpu_cmpxchg_8
+#  define this_cpu_cmpxchg_8(pcp, old, new) this_cpu_cmpxchg_generic((pcp), (old), (new), 8)
+# endif
+# define this_cpu_cmpxchg(pcp, old, new) __pcpu_size_call_return(__this_cpu_cmpxchg_, (old), (new))
+#endif
+
 /*
  * Generic percpu operations that do not require preemption handling.
  * Either we do not care about races or the caller has the
@@ -594,6 +650,22 @@ do {									\
 # define __this_cpu_xor(pcp, val)	__pcpu_size_call(__this_cpu_xor_, (pcp), (val))
 #endif
 
+#ifndef __this_cpu_cmpxchg
+# ifndef __this_cpu_cmpxchg_1
+#  define __this_cpu_cmpxchg_1(pcp, old, new) __this_cpu_cmpxchg_generic((pcp), (old), (new), 1)
+# endif
+# ifndef __this_cpu_cmpxchg_2
+#  define __this_cpu_cmpxchg_2(pcp, old, new) __this_cpu_cmpxchg_generic((pcp), (old), (new), 2)
+# endif
+# ifndef __this_cpu_cmpxchg_4
+#  define __this_cpu_cmpxchg_4(pcp, old, new) __this_cpu_cmpxchg_generic((pcp), (old), (new), 4)
+# endif
+# ifndef __this_cpu_cmpxchg_8
+#  define __this_cpu_cmpxchg_8(pcp, old, new) __this_cpu_cmpxchg_generic((pcp), (old), (new), 8)
+# endif
+# define __this_cpu_cmpxchg(pcp, old, new) __pcpu_size_call_return(__this_cpu_cmpxchg_, (old), (new))
+#endif
+
 /*
  * IRQ safe versions of the per cpu RMW operations. Note that these operations
  * are *not* safe against modification of the same variable from another
@@ -709,4 +781,31 @@ do {									\
 # define irqsafe_cpu_xor(pcp, val) __pcpu_size_call(irqsafe_cpu_xor_, (val))
 #endif
 
+static inline unsigned long irqsafe_cpu_cmpxchg_generic(volatile void *ptr,
+		unsigned long old, unsigned long new, int size)
+{
+	unsigned long flags, prev;
+
+	local_irq_save(flags);
+	prev = __this_cpu_cmpxchg_generic(ptr, old, new, size);
+	local_irq_restore(flags);
+	return prev;
+}
+
+#ifndef irqsafe_cpu_cmpxchg
+# ifndef irqsafe_cpu_cmpxchg_1
+#  define irqsafe_cpu_cmpxchg_1(pcp, old, new) irqsafe_cpu_cmpxchg_generic(((pcp), (old), (new), 1)
+# endif
+# ifndef irqsafe_cpu_cmpxchg_2
+#  define irqsafe_cpu_cmpxchg_2(pcp, old, new) irqsafe_cpu_cmpxchg_generic(((pcp), (old), (new), 2)
+# endif
+# ifndef irqsafe_cpu_cmpxchg_4
+#  define irqsafe_cpu_cmpxchg_4(pcp, old, new) irqsafe_cpu_cmpxchg_generic(((pcp), (old), (new), 4)
+# endif
+# ifndef irqsafe_cpu_cmpxchg_8
+#  define irqsafe_cpu_cmpxchg_8(pcp, old, new) irqsafe_cpu_cmpxchg_generic(((pcp), (old), (new), 8)
+# endif
+# define irqsafe_cpu_cmpxchg(pcp, old, new) __pcpu_size_call_return(irqsafe_cpu_cmpxchg_, (old), (new))
+#endif
+
 #endif /* __LINUX_PERCPU_H */

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