Commit 67473b81 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

xen/events: Remove disfunct affinity spreading 



This function can only ever work when the event channels:

  - are already established
  - interrupts assigned to them
  - the affinity has been set by user space already

because any newly set up event channel is forced to be bound to CPU0 and
the affinity mask of the interrupt is forced to contain cpumask_of(0).

As the CPU0 enforcement was in place _before_ this was implemented it's
entirely unclear how that can ever have worked at all.

Remove it as preparation for doing it proper.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20201210194045.065115500@linutronix.de
parent 3bd5371a

drivers/xen/events/events_base.c

+0 −9
Original line number Diff line number Diff line
@@ -1696,15 +1696,6 @@ static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest, 
	return ret;

}



/* To be called with desc->lock held. */

int xen_set_affinity_evtchn(struct irq_desc *desc, unsigned int tcpu)

{

	struct irq_data *d = irq_desc_get_irq_data(desc);



	return set_affinity_irq(d, cpumask_of(tcpu), false);

}

EXPORT_SYMBOL_GPL(xen_set_affinity_evtchn);



static void enable_dynirq(struct irq_data *data)

{

	evtchn_port_t evtchn = evtchn_from_irq(data->irq);

drivers/xen/evtchn.c

+1 −33
Original line number Diff line number Diff line
@@ -421,36 +421,6 @@ static void evtchn_unbind_from_user(struct per_user_data *u, 
	del_evtchn(u, evtchn);

}



static DEFINE_PER_CPU(int, bind_last_selected_cpu);



static void evtchn_bind_interdom_next_vcpu(evtchn_port_t evtchn)

{

	unsigned int selected_cpu, irq;

	struct irq_desc *desc;

	unsigned long flags;



	irq = irq_from_evtchn(evtchn);

	desc = irq_to_desc(irq);



	if (!desc)

		return;



	raw_spin_lock_irqsave(&desc->lock, flags);

	selected_cpu = this_cpu_read(bind_last_selected_cpu);

	selected_cpu = cpumask_next_and(selected_cpu,

			desc->irq_common_data.affinity, cpu_online_mask);



	if (unlikely(selected_cpu >= nr_cpu_ids))

		selected_cpu = cpumask_first_and(desc->irq_common_data.affinity,

				cpu_online_mask);



	this_cpu_write(bind_last_selected_cpu, selected_cpu);



	/* unmask expects irqs to be disabled */

	xen_set_affinity_evtchn(desc, selected_cpu);

	raw_spin_unlock_irqrestore(&desc->lock, flags);

}



static long evtchn_ioctl(struct file *file,

			 unsigned int cmd, unsigned long arg)

{
@@ -508,10 +478,8 @@ static long evtchn_ioctl(struct file *file, 
			break;



		rc = evtchn_bind_to_user(u, bind_interdomain.local_port);

		if (rc == 0) {

		if (rc == 0)

			rc = bind_interdomain.local_port;

			evtchn_bind_interdom_next_vcpu(rc);

		}

		break;

	}

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