Commit 4db2ce01 authored by David S. Miller's avatar David S. Miller
Browse files

[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: default avatarDavid S. Miller <davem@davemloft.net>
parent 4a805e86

arch/i386/Kconfig

+0 −5
Original line number Diff line number Diff line
@@ -908,11 +908,6 @@ config IRQBALANCE 
 	  The default yes will allow the kernel to do irq load balancing.

	  Saying no will keep the kernel from doing irq load balancing.



config HAVE_DEC_LOCK

	bool

	depends on (SMP || PREEMPT) && X86_CMPXCHG

	default y



# turning this on wastes a bunch of space.

# Summit needs it only when NUMA is on

config BOOT_IOREMAP

arch/i386/lib/Makefile

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Original line number Diff line number Diff line
@@ -7,4 +7,3 @@ lib-y = checksum.o delay.o usercopy.o getuser.o putuser.o memcpy.o strstr.o \ 
	bitops.o



lib-$(CONFIG_X86_USE_3DNOW) += mmx.o
 
lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o

arch/i386/lib/dec_and_lock.c

deleted100644 → 0
+0 −42
Original line number Diff line number Diff line 
/*

 * x86 version of "atomic_dec_and_lock()" using

 * the atomic "cmpxchg" instruction.

 *

 * (For CPU's lacking cmpxchg, we use the slow

 * generic version, and this one never even gets

 * compiled).

 */



#include <linux/spinlock.h>

#include <linux/module.h>

#include <asm/atomic.h>



int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)

{

	int counter;

	int newcount;



repeat:

	counter = atomic_read(atomic);

	newcount = counter-1;



	if (!newcount)

		goto slow_path;



	asm volatile("lock; cmpxchgl %1,%2"

		:"=a" (newcount)

		:"r" (newcount), "m" (atomic->counter), "0" (counter));



	/* If the above failed, "eax" will have changed */

	if (newcount != counter)

		goto repeat;

	return 0;



slow_path:

	spin_lock(lock);

	if (atomic_dec_and_test(atomic))

		return 1;

	spin_unlock(lock);

	return 0;

}

EXPORT_SYMBOL(_atomic_dec_and_lock);

arch/ia64/Kconfig

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Original line number Diff line number Diff line
@@ -298,11 +298,6 @@ config PREEMPT 


source "mm/Kconfig"



config HAVE_DEC_LOCK

	bool

	depends on (SMP || PREEMPT)

	default y



config IA32_SUPPORT

	bool "Support for Linux/x86 binaries"

	help

arch/ia64/lib/Makefile

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Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ lib-$(CONFIG_ITANIUM) += copy_page.o copy_user.o memcpy.o 
lib-$(CONFIG_MCKINLEY)	+= copy_page_mck.o memcpy_mck.o

lib-$(CONFIG_PERFMON)	+= carta_random.o

lib-$(CONFIG_MD_RAID5)	+= xor.o

lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o



AFLAGS___divdi3.o	=

AFLAGS___udivdi3.o	= -DUNSIGNED

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