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Pull ticket-spinaphore into release branch
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commit
8add570a70
1 changed files with 18 additions and 6 deletions
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@ -100,24 +100,36 @@ wrap_mmu_context (struct mm_struct *mm)
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* this primitive it can be moved up to a spinaphore.h header.
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*/
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struct spinaphore {
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atomic_t cur;
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unsigned long ticket;
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unsigned long serve;
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};
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static inline void spinaphore_init(struct spinaphore *ss, int val)
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{
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atomic_set(&ss->cur, val);
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ss->ticket = 0;
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ss->serve = val;
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}
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static inline void down_spin(struct spinaphore *ss)
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{
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while (unlikely(!atomic_add_unless(&ss->cur, -1, 0)))
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while (atomic_read(&ss->cur) == 0)
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cpu_relax();
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unsigned long t = ia64_fetchadd(1, &ss->ticket, acq), serve;
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if (time_before(t, ss->serve))
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return;
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ia64_invala();
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for (;;) {
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asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
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if (time_before(t, serve))
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return;
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cpu_relax();
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}
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}
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static inline void up_spin(struct spinaphore *ss)
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{
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atomic_add(1, &ss->cur);
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ia64_fetchadd(1, &ss->serve, rel);
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}
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static struct spinaphore ptcg_sem;
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