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@xxxxxxxxx>
---
diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c
index f426dc7..ee09d26 100644
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -100,24 +100,36 @@ wrap_mmu_context (struct mm_struct *mm)
* this primitive it can be moved up to a spinaphore.h header.
*/
struct spinaphore {
- atomic_t cur;
+ unsigned long ticket;
+ unsigned long serve;
};
static inline void spinaphore_init(struct spinaphore *ss, int val)
{
- atomic_set(&ss->cur, val);
+ ss->ticket = 0;
+ ss->serve = val;
}
static inline void down_spin(struct spinaphore *ss)
{
- while (unlikely(!atomic_add_unless(&ss->cur, -1, 0)))
- while (atomic_read(&ss->cur) == 0)
- cpu_relax();
+ unsigned long t = ia64_fetchadd(1, &ss->ticket, acq), serve;
+
+ if (time_before(t, ss->serve))
+ return;
+
+ ia64_invala();
+
+ for (;;) {
+ asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
+ if (time_before(t, serve))
+ return;
+ cpu_relax();
+ }
}
static inline void up_spin(struct spinaphore *ss)
{
- atomic_add(1, &ss->cur);
+ ia64_fetchadd(1, &ss->serve, rel);
}
static struct spinaphore ptcg_sem;
--
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