dec_and_lock.c

Go to the documentation of this file.

/*
 * arch/alpha/lib/dec_and_lock.c
 *
 * ll/sc version of atomic_dec_and_lock()
 * 
 */

#include <linux/spinlock.h>
#include <linux/atomic.h>

  asm (".text                   \n\
    .global _atomic_dec_and_lock        \n\
    .ent _atomic_dec_and_lock       \n\
    .align  4               \n\
_atomic_dec_and_lock:               \n\
    .prologue 0             \n\
1:  ldl_l   $1, 0($16)          \n\
    subl    $1, 1, $1           \n\
    beq $1, 2f              \n\
    stl_c   $1, 0($16)          \n\
    beq $1, 4f              \n\
    mb                  \n\
    clr $0              \n\
    ret                 \n\
2:  br  $29, 3f             \n\
3:  ldgp    $29, 0($29)         \n\
    br  $atomic_dec_and_lock_1..ng  \n\
    .subsection 2               \n\
4:  br  1b              \n\
    .previous               \n\
    .end _atomic_dec_and_lock");

static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
{
    /* Slow path */
    spin_lock(lock);
    if (atomic_dec_and_test(atomic))
        return 1;
    spin_unlock(lock);
    return 0;
}