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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [include/] [asm-i386/] [locks.h] - Blame information for rev 1777

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Line No. Rev Author Line
1 1633 jcastillo 
/*
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 *      SMP locks primitives for building ix86 locks
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 *      (not yet used).
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 *
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 *              Alan Cox, alan@cymru.net, 1995
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 */
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/*
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 *      This would be much easier but far less clear and easy
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 *      to borrow for other processors if it was just assembler.
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 */
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extern __inline__ void prim_spin_lock(struct spinlock *sp)
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{
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        int processor=smp_processor_id();
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        /*
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         *      Grab the lock bit
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         */
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        while(lock_set_bit(0,&sp->lock))
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        {
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                /*
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                 *      Failed, but that's cos we own it!
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                 */
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                if(sp->cpu==processor)
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                {
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                        sp->users++;
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                        return 0;
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                }
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                /*
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                 *      Spin in the cache S state if possible
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                 */
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                while(sp->lock)
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                {
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                        /*
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                         *      Wait for any invalidates to go off
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                         */
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                        if(smp_invalidate_needed&(1<<processor))
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                                while(lock_clear_bit(processor,&smp_invalidate_needed))
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                                        local_flush_tlb();
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                        sp->spins++;
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                }
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                /*
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                 *      Someone wrote the line, we go 'I' and get
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                 *      the cache entry. Now try to regrab
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                 */
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        }
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        sp->users++;sp->cpu=processor;
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        return 1;
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}
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/*
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 *      Release a spin lock
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 */
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extern __inline__ int prim_spin_unlock(struct spinlock *sp)
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{
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        /* This is safe. The decrement is still guarded by the lock. A multilock would
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           not be safe this way */
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        if(!--sp->users)
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        {
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                lock_clear_bit(0,&sp->lock);sp->cpu= NO_PROC_ID;
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                return 1;
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        }
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        return 0;
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}
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/*
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 *      Non blocking lock grab
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 */
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extern __inline__ int prim_spin_lock_nb(struct spinlock *sp)
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{
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        if(lock_set_bit(0,&sp->lock))
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                return 0;                /* Locked already */
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        sp->users++;
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        return 1;                       /* We got the lock */
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}
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/*
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 *      These wrap the locking primitives up for usage
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 */
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extern __inline__ void spinlock(struct spinlock *sp)
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{
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        if(sp->priority<current->lock_order)
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                panic("lock order violation: %s (%d)\n", sp->name, current->lock_order);
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        if(prim_spin_lock(sp))
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        {
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                /*
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                 *      We got a new lock. Update the priority chain
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                 */
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                sp->oldpri=current->lock_order;
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                current->lock_order=sp->priority;
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        }
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}
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extern __inline__ void spinunlock(struct spinlock *sp)
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{
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        if(current->lock_order!=sp->priority)
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                panic("lock release order violation %s (%d)\n", sp->name, current->lock_order);
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        if(prim_spin_unlock(sp))
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        {
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                /*
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                 *      Update the debugging lock priority chain. We dumped
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                 *      our last right to the lock.
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                 */
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                current->lock_order=sp->oldpri;
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        }
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}
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extern __inline__ void spintestlock(struct spinlock *sp)
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{
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        /*
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         *      We do no sanity checks, it's legal to optimistically
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         *      get a lower lock.
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         */
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        prim_spin_lock_nb(sp);
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}
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extern __inline__ void spintestunlock(struct spinlock *sp)
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{
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        /*
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         *      A testlock doesn't update the lock chain so we
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         *      must not update it on free
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         */
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        prim_spin_unlock(sp);
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}

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