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-rw-r--r--arch/x86/include/asm/spinlock.h14
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index bf156ded74b5..abc34e95398d 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -184,8 +184,20 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
{
- while (arch_spin_is_locked(lock))
+ __ticket_t head = ACCESS_ONCE(lock->tickets.head);
+
+ for (;;) {
+ struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
+ /*
+ * We need to check "unlocked" in a loop, tmp.head == head
+ * can be false positive because of overflow.
+ */
+ if (tmp.head == (tmp.tail & ~TICKET_SLOWPATH_FLAG) ||
+ tmp.head != head)
+ break;
+
cpu_relax();
+ }
}
/*