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Commit 229855d6 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by H. Peter Anvin
Browse files

x86, ticketlock: Make __ticket_spin_trylock common 



Make trylock code common regardless of ticket size.

(Also, rename arch_spinlock.slock to head_tail.)

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 2994488f

arch/x86/include/asm/spinlock.h

+12 −39
Original line number Original line Diff line number Diff line
@@ -69,60 +69,33 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) 
	barrier();		/* make sure nothing creeps before the lock is taken */

	barrier();		/* make sure nothing creeps before the lock is taken */

}

}





#if (NR_CPUS < 256)

static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)

static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)

{

{

	unsigned int tmp, new;

	arch_spinlock_t old, new;



	asm volatile("movzwl %2, %0\n\t"

		     "cmpb %h0,%b0\n\t"

		     "leal 0x100(%" REG_PTR_MODE "0), %1\n\t"

		     "jne 1f\n\t"

		     LOCK_PREFIX "cmpxchgw %w1,%2\n\t"

		     "1:"

		     "sete %b1\n\t"

		     "movzbl %b1,%0\n\t"

		     : "=&a" (tmp), "=&q" (new), "+m" (lock->slock)

		     :

		     : "memory", "cc");





	return tmp;

	old.tickets = ACCESS_ONCE(lock->tickets);

	if (old.tickets.head != old.tickets.tail)

		return 0;



	new.head_tail = old.head_tail + (1 << TICKET_SHIFT);



	/* cmpxchg is a full barrier, so nothing can move before it */

	return cmpxchg(&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail;

}

}





#if (NR_CPUS < 256)

static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)

static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)

{

{

	asm volatile(UNLOCK_LOCK_PREFIX "incb %0"

	asm volatile(UNLOCK_LOCK_PREFIX "incb %0"

		     : "+m" (lock->slock)

		     : "+m" (lock->head_tail)

		     :

		     :

		     : "memory", "cc");

		     : "memory", "cc");

}

}

#else

#else

static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)

{

	unsigned tmp;

	unsigned new;



	asm volatile("movl %2,%0\n\t"

		     "movl %0,%1\n\t"

		     "roll $16, %0\n\t"

		     "cmpl %0,%1\n\t"

		     "leal 0x00010000(%" REG_PTR_MODE "0), %1\n\t"

		     "jne 1f\n\t"

		     LOCK_PREFIX "cmpxchgl %1,%2\n\t"

		     "1:"

		     "sete %b1\n\t"

		     "movzbl %b1,%0\n\t"

		     : "=&a" (tmp), "=&q" (new), "+m" (lock->slock)

		     :

		     : "memory", "cc");



	return tmp;

}



static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)

static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)

{

{

	asm volatile(UNLOCK_LOCK_PREFIX "incw %0"

	asm volatile(UNLOCK_LOCK_PREFIX "incw %0"

		     : "+m" (lock->slock)

		     : "+m" (lock->head_tail)

		     :

		     :

		     : "memory", "cc");

		     : "memory", "cc");

}

}

arch/x86/include/asm/spinlock_types.h

+4 −2
Original line number Original line Diff line number Diff line
@@ -9,8 +9,10 @@ 




#if (CONFIG_NR_CPUS < 256)

#if (CONFIG_NR_CPUS < 256)

typedef u8  __ticket_t;

typedef u8  __ticket_t;

typedef u16 __ticketpair_t;

#else

#else

typedef u16 __ticket_t;

typedef u16 __ticket_t;

typedef u32 __ticketpair_t;

#endif

#endif





#define TICKET_SHIFT	(sizeof(__ticket_t) * 8)

#define TICKET_SHIFT	(sizeof(__ticket_t) * 8)
@@ -18,14 +20,14 @@ typedef u16 __ticket_t; 




typedef struct arch_spinlock {

typedef struct arch_spinlock {

	union {

	union {

		unsigned int slock;

		__ticketpair_t head_tail;

		struct __raw_tickets {

		struct __raw_tickets {

			__ticket_t head, tail;

			__ticket_t head, tail;

		} tickets;

		} tickets;

	};

	};

} arch_spinlock_t;

} arch_spinlock_t;





#define __ARCH_SPIN_LOCK_UNLOCKED	{ { .slock = 0 } }

#define __ARCH_SPIN_LOCK_UNLOCKED	{ { 0 } }





#include <asm/rwlock.h>

#include <asm/rwlock.h>