PTHREAD_PRIO_INHERIT support for ARM.

This patch implements the futex_atomic_cmpxchg_inatomic() for the
ARM architecture. Without this patch the userland PI mutex will
not work.

Signed-off-by: Remy Bohmer <linux@bohmer.net>
---
# include/asm-arm/futex.h |   64 +++++++++++++++++++++++++++++++++++++++++++++---
# 1 file changed, 61 insertions(+), 3 deletions(-)
#
Index: linux-2.6.22/include/asm-arm/futex.h
===================================================================
--- linux-2.6.22.orig/include/asm-arm/futex.h	2007-07-09 01:32:17.000000000 +0200
+++ linux-2.6.22/include/asm-arm/futex.h	2007-07-24 17:05:26.000000000 +0200
@@ -1,6 +1,64 @@
-#ifndef _ASM_FUTEX_H
-#define _ASM_FUTEX_H
+#ifndef _ASM_ARM_FUTEX_H
+#define _ASM_ARM_FUTEX_H
 
-#include <asm-generic/futex.h>
+#ifdef __KERNEL__
 
+#include <linux/futex.h>
+#include <linux/errno.h>
+#include <linux/uaccess.h>
+#include <asm/atomic.h>
+
+static inline int
+futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
+{
+	int op = (encoded_op >> 28) & 7;
+	int cmp = (encoded_op >> 24) & 15;
+	int oparg = (encoded_op << 8) >> 20;
+	int cmparg = (encoded_op << 20) >> 20;
+	int oldval = 0;
+	int ret;
+	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+		oparg = 1 << oparg;
+
+	if (!access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
+		return -EFAULT;
+
+	pagefault_disable();
+
+	switch (op) {
+	case FUTEX_OP_SET:
+	case FUTEX_OP_ADD:
+	case FUTEX_OP_OR:
+	case FUTEX_OP_ANDN:
+	case FUTEX_OP_XOR:
+	default:
+		ret = -ENOSYS;
+	}
+
+	pagefault_enable();
+
+	if (!ret) {
+		switch (cmp) {
+		case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
+		case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
+		case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
+		case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
+		case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
+		case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
+		default: ret = -ENOSYS;
+		}
+	}
+	return ret;
+}
+
+static inline int
+futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
+{
+	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+		return -EFAULT;
+
+	return cmpxchg(uaddr, oldval, newval);
+}
+
+#endif
 #endif