[IA64] Re-implement spinaphores using ticket lock concepts
Bound the wait time for the ptcg_sem by using similar idea to the ticket spin locks. In this case we have only one instance of a spinaphore, so make it 8 bytes rather than try to squeeze it into 4-bytes to keep the code simpler (and shorter). Signed-off-by: Tony Luck <tony.luck@intel.com>
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36a07902c2
Коммит
883a3acf5b
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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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