Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

arch/sparc64/lib/dec_and_lock.S

@@ -0,0 +1,78 @@
+/* $Id: dec_and_lock.S,v 1.5 2001/11/18 00:12:56 davem Exp $
+ * dec_and_lock.S: Sparc64 version of "atomic_dec_and_lock()"
+ *                 using cas and ldstub instructions.
+ *
+ * Copyright (C) 2000 David S. Miller (davem@redhat.com)
+ */
+#include <linux/config.h>
+#include <asm/thread_info.h>
+
+	.text
+	.align	64
+
+	/* CAS basically works like this:
+	 *
+	 * void CAS(MEM, REG1, REG2)
+	 * {
+	 *   START_ATOMIC();
+	 *   if (*(MEM) == REG1) {
+	 *     TMP = *(MEM);
+	 *     *(MEM) = REG2;
+	 *     REG2 = TMP;
+	 *   } else
+	 *     REG2 = *(MEM);
+	 *   END_ATOMIC();
+	 * }
+	 */
+
+	.globl	_atomic_dec_and_lock
+_atomic_dec_and_lock:	/* %o0 = counter, %o1 = lock */
+loop1:	lduw	[%o0], %g2
+	subcc	%g2, 1, %g7
+	be,pn	%icc, start_to_zero
+	 nop
+nzero:	cas	[%o0], %g2, %g7
+	cmp	%g2, %g7
+	bne,pn	%icc, loop1
+	 mov	0, %g1
+
+out:
+	membar	#StoreLoad | #StoreStore
+	retl
+	 mov	%g1, %o0
+start_to_zero:
+#ifdef CONFIG_PREEMPT
+	ldsw	[%g6 + TI_PRE_COUNT], %g3
+	add	%g3, 1, %g3
+	stw	%g3, [%g6 + TI_PRE_COUNT]
+#endif
+to_zero:
+	ldstub	[%o1], %g3
+	brnz,pn	%g3, spin_on_lock
+	 membar	#StoreLoad | #StoreStore
+loop2:	cas	[%o0], %g2, %g7		/* ASSERT(g7 == 0) */
+	cmp	%g2, %g7
+
+	be,pt	%icc, out
+	 mov	1, %g1
+	lduw	[%o0], %g2
+	subcc	%g2, 1, %g7
+	be,pn	%icc, loop2
+	 nop
+	membar	#StoreStore | #LoadStore
+	stb	%g0, [%o1]
+#ifdef CONFIG_PREEMPT
+	ldsw	[%g6 + TI_PRE_COUNT], %g3
+	sub	%g3, 1, %g3
+	stw	%g3, [%g6 + TI_PRE_COUNT]
+#endif
+
+	b,pt	%xcc, nzero
+	 nop
+spin_on_lock:
+	ldub	[%o1], %g3
+	brnz,pt	%g3, spin_on_lock
+	 membar	#LoadLoad
+	ba,pt	%xcc, to_zero
+	 nop
+	nop