diff options
| -rw-r--r-- | arch/x86/include/asm/spinlock.h | 14 |
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(); + } } /* |