2 * SMP locks primitives for building ix86 locks
5 * Alan Cox, alan@cymru.net, 1995
9 * This would be much easier but far less clear and easy
10 * to borrow for other processors if it was just assembler.
13 extern __inline__ void prim_spin_lock(struct spinlock *sp)
15 int processor=smp_processor_id();
21 while(lock_set_bit(0,&sp->lock))
24 * Failed, but that's cos we own it!
27 if(sp->cpu==processor)
33 * Spin in the cache S state if possible
38 * Wait for any invalidates to go off
41 if(smp_invalidate_needed&(1<<processor))
42 while(lock_clear_bit(processor,&smp_invalidate_needed))
47 * Someone wrote the line, we go 'I' and get
48 * the cache entry. Now try to regrab
51 sp->users++;sp->cpu=processor;
59 extern __inline__ int prim_spin_unlock(struct spinlock *sp)
61 /* This is safe. The decrement is still guarded by the lock. A multilock would
62 not be safe this way */
65 lock_clear_bit(0,&sp->lock);sp->cpu= NO_PROC_ID;
73 * Non blocking lock grab
76 extern __inline__ int prim_spin_lock_nb(struct spinlock *sp)
78 if(lock_set_bit(0,&sp->lock))
79 return 0; /* Locked already */
81 return 1; /* We got the lock */
86 * These wrap the locking primitives up for usage
89 extern __inline__ void spinlock(struct spinlock *sp)
91 if(sp->priority<current->lock_order)
92 panic("lock order violation: %s (%d)\n", sp->name, current->lock_order);
93 if(prim_spin_lock(sp))
96 * We got a new lock. Update the priority chain
98 sp->oldpri=current->lock_order;
99 current->lock_order=sp->priority;
103 extern __inline__ void spinunlock(struct spinlock *sp)
105 if(current->lock_order!=sp->priority)
106 panic("lock release order violation %s (%d)\n", sp->name, current->lock_order);
107 if(prim_spin_unlock(sp))
110 * Update the debugging lock priority chain. We dumped
111 * our last right to the lock.
113 current->lock_order=sp->oldpri;
117 extern __inline__ void spintestlock(struct spinlock *sp)
120 * We do no sanity checks, it's legal to optimistically
123 prim_spin_lock_nb(sp);
126 extern __inline__ void spintestunlock(struct spinlock *sp)
129 * A testlock doesn't update the lock chain so we
130 * must not update it on free
132 prim_spin_unlock(sp);