Re: [PATCH 2/2] xen: make xen_qlock_wait() nestable

On Mon, 2018-10-01 at 09:16 +0200, Juergen Gross wrote:

•   /* If irq pending already clear it and return. */
  

•   /* Guard against reentry. */
  

•   local_irq_save(flags);
  

•   /* If irq pending already clear it. */
    if (xen_test_irq_pending(irq)) {
            xen_clear_irq_pending(irq);
  

•           return;
  

•   } else if (READ_ONCE(*byte) == val) {
  

•           /* Block until irq becomes pending (or a spurious wakeup) */
  

•           xen_poll_irq(irq);
    }
  

Does this still allow other IRQs to wake it from xen_poll_irq()?

In the case where process-context code is spinning for a lock without disabling interrupts, we *should* allow interrupts to occur still... does this?