07-24-2023, 10:53 AM
Here is my implementation of a spin lock, but it seems it can not protect the critical code. Is there something wrong with my implementation?
static __inline__ int xchg_asm(int* lock, int val)
{
int ret;
__asm__ __volatile__(
LOCK "movl (%1),%%eax;
xchg (%1),%2;
movl %%eax, %0" :"=m" (ret) :"d"(lock), "c"(val)
);
return ret;
}
void spin_init(spinlock_t* sl)
{
sl->val = 0;
}
void spin_lock(spinlock_t* sl)
{
int ret;
do {
ret = xchg_asm(&(sl->val), 1);
} while ( ret==0 );
}
void spin_unlock(spinlock_t* sl)
{
xchg_asm(&(sl->val), 0);
}
static __inline__ int xchg_asm(int* lock, int val)
{
int ret;
__asm__ __volatile__(
LOCK "movl (%1),%%eax;
xchg (%1),%2;
movl %%eax, %0" :"=m" (ret) :"d"(lock), "c"(val)
);
return ret;
}
void spin_init(spinlock_t* sl)
{
sl->val = 0;
}
void spin_lock(spinlock_t* sl)
{
int ret;
do {
ret = xchg_asm(&(sl->val), 1);
} while ( ret==0 );
}
void spin_unlock(spinlock_t* sl)
{
xchg_asm(&(sl->val), 0);
}