diff options
Diffstat (limited to 'arch/x86/xen/spinlock.c')
| -rw-r--r-- | arch/x86/xen/spinlock.c | 44 |
1 files changed, 18 insertions, 26 deletions
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 973f10e05211..441c88262169 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -39,34 +39,25 @@ static void xen_qlock_kick(int cpu) */ static void xen_qlock_wait(u8 *byte, u8 val) { + unsigned long flags; int irq = __this_cpu_read(lock_kicker_irq); /* If kicker interrupts not initialized yet, just spin */ - if (irq == -1) + if (irq == -1 || in_nmi()) return; - /* clear pending */ - xen_clear_irq_pending(irq); - barrier(); - - /* - * We check the byte value after clearing pending IRQ to make sure - * that we won't miss a wakeup event because of the clearing. - * - * The sync_clear_bit() call in xen_clear_irq_pending() is atomic. - * So it is effectively a memory barrier for x86. - */ - if (READ_ONCE(*byte) != val) - return; + /* Guard against reentry. */ + local_irq_save(flags); - /* - * If an interrupt happens here, it will leave the wakeup irq - * pending, which will cause xen_poll_irq() to return - * immediately. - */ + /* If irq pending already clear it. */ + if (xen_test_irq_pending(irq)) { + xen_clear_irq_pending(irq); + } else if (READ_ONCE(*byte) == val) { + /* Block until irq becomes pending (or a spurious wakeup) */ + xen_poll_irq(irq); + } - /* Block until irq becomes pending (or perhaps a spurious wakeup) */ - xen_poll_irq(irq); + local_irq_restore(flags); } static irqreturn_t dummy_handler(int irq, void *dev_id) @@ -141,11 +132,12 @@ void __init xen_init_spinlocks(void) printk(KERN_DEBUG "xen: PV spinlocks enabled\n"); __pv_init_lock_hash(); - pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; - pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); - pv_lock_ops.wait = xen_qlock_wait; - pv_lock_ops.kick = xen_qlock_kick; - pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen); + pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_ops.lock.queued_spin_unlock = + PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_ops.lock.wait = xen_qlock_wait; + pv_ops.lock.kick = xen_qlock_kick; + pv_ops.lock.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen); } static __init int xen_parse_nopvspin(char *arg) |