[LIB]: Consolidate _atomic_dec_and_lock()

Several implementations were essentialy a common piece of C code using
the cmpxchg() macro.  Put the implementation in one spot that everyone
can share, and convert sparc64 over to using this.

Alpha is the lone arch-specific implementation, which codes up a
special fast path for the common case in order to avoid GP reloading
which a pure C version would require.

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 0 insertions, 93 deletions

diff --git a/arch/sparc64/Kconfig.debug b/arch/sparc64/Kconfig.debug
index cd8d39fb954d..af0e9411b83e 100644
--- a/arch/sparc64/Kconfig.debug
+++ b/arch/sparc64/Kconfig.debug
@@ -33,14 +33,6 @@ config DEBUG_BOOTMEM
 	depends on DEBUG_KERNEL
 	bool "Debug BOOTMEM initialization"
 
-# We have a custom atomic_dec_and_lock() implementation but it's not
-# compatible with spinlock debugging so we need to fall back on
-# the generic version in that case.
-config HAVE_DEC_LOCK
-	bool
-	depends on SMP && !DEBUG_SPINLOCK
-	default y
-
 config MCOUNT
 	bool
 	depends on STACK_DEBUG
diff --git a/arch/sparc64/kernel/sparc64_ksyms.c b/arch/sparc64/kernel/sparc64_ksyms.c
index cbb5e59824e5..fb7a5370dbfc 100644
--- a/arch/sparc64/kernel/sparc64_ksyms.c
+++ b/arch/sparc64/kernel/sparc64_ksyms.c
@@ -163,9 +163,6 @@ EXPORT_SYMBOL(atomic64_add);
 EXPORT_SYMBOL(atomic64_add_ret);
 EXPORT_SYMBOL(atomic64_sub);
 EXPORT_SYMBOL(atomic64_sub_ret);
-#ifdef CONFIG_SMP
-EXPORT_SYMBOL(_atomic_dec_and_lock);
-#endif
 
 /* Atomic bit operations. */
 EXPORT_SYMBOL(test_and_set_bit);
diff --git a/arch/sparc64/lib/Makefile b/arch/sparc64/lib/Makefile
index d968aebe83b2..c295806500f7 100644
--- a/arch/sparc64/lib/Makefile
+++ b/arch/sparc64/lib/Makefile
@@ -14,6 +14,4 @@ lib-y := PeeCeeI.o copy_page.o clear_page.o strlen.o strncmp.o \
 	 copy_in_user.o user_fixup.o memmove.o \
 	 mcount.o ipcsum.o rwsem.o xor.o find_bit.o delay.o
 
-lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o
-
 obj-y += iomap.o
diff --git a/arch/sparc64/lib/dec_and_lock.S b/arch/sparc64/lib/dec_and_lock.S
deleted file mode 100644
index 8ee288dd0afc..000000000000
--- a/arch/sparc64/lib/dec_and_lock.S
+++ /dev/null
@@ -1,80 +0,0 @@
-/* $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
-	membar	#StoreLoad | #StoreStore
-	brnz,pn	%g3, spin_on_lock
-	 nop
-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
-	membar	#LoadLoad
-	brnz,pt	%g3, spin_on_lock
-	 nop
-	ba,pt	%xcc, to_zero
-	 nop
-	nop