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/*
* SMP locks primitives for building ix86 locks
* (not yet used).
*
* Alan Cox, alan@redhat.com, 1995
*/
/*
* This would be much easier but far less clear and easy
* to borrow for other processors if it was just assembler.
*/
static __inline__ void prim_spin_lock(struct spinlock *sp)
{
int processor=smp_processor_id();
/*
* Grab the lock bit
*/
while(lock_set_bit(0,&sp->lock))
{
/*
* Failed, but that's cos we own it!
*/
if(sp->cpu==processor)
{
sp->users++;
return 0;
}
/*
* Spin in the cache S state if possible
*/
while(sp->lock)
{
/*
* Wait for any invalidates to go off
*/
if(smp_invalidate_needed&(1<<processor))
while(lock_clear_bit(processor,&smp_invalidate_needed))
local_flush_tlb();
sp->spins++;
}
/*
* Someone wrote the line, we go 'I' and get
* the cache entry. Now try to regrab
*/
}
sp->users++;sp->cpu=processor;
return 1;
}
/*
* Release a spin lock
*/
static __inline__ int prim_spin_unlock(struct spinlock *sp)
{
/* This is safe. The decrement is still guarded by the lock. A multilock would
not be safe this way */
if(!--sp->users)
{
sp->cpu= NO_PROC_ID;lock_clear_bit(0,&sp->lock);
return 1;
}
return 0;
}
/*
* Non blocking lock grab
*/
static __inline__ int prim_spin_lock_nb(struct spinlock *sp)
{
if(lock_set_bit(0,&sp->lock))
return 0; /* Locked already */
sp->users++;
return 1; /* We got the lock */
}
/*
* These wrap the locking primitives up for usage
*/
static __inline__ void spinlock(struct spinlock *sp)
{
if(sp->priority<current->lock_order)
panic("lock order violation: %s (%d)\n", sp->name, current->lock_order);
if(prim_spin_lock(sp))
{
/*
* We got a new lock. Update the priority chain
*/
sp->oldpri=current->lock_order;
current->lock_order=sp->priority;
}
}
static __inline__ void spinunlock(struct spinlock *sp)
{
int pri;
if(current->lock_order!=sp->priority)
panic("lock release order violation %s (%d)\n", sp->name, current->lock_order);
pri=sp->oldpri;
if(prim_spin_unlock(sp))
{
/*
* Update the debugging lock priority chain. We dumped
* our last right to the lock.
*/
current->lock_order=sp->pri;
}
}
static __inline__ void spintestlock(struct spinlock *sp)
{
/*
* We do no sanity checks, it's legal to optimistically
* get a lower lock.
*/
prim_spin_lock_nb(sp);
}
static __inline__ void spintestunlock(struct spinlock *sp)
{
/*
* A testlock doesn't update the lock chain so we
* must not update it on free
*/
prim_spin_unlock(sp);
}
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