Commit 3de218ff authored by Juergen Gross's avatar Juergen Gross
Browse files

xen/events: reset active flag for lateeoi events later 



In order to avoid a race condition for user events when changing
cpu affinity reset the active flag only when EOI-ing the event.

This is working fine as all user events are lateeoi events. Note that
lateeoi_ack_mask_dynirq() is not modified as there is no explicit call
to xen_irq_lateeoi() expected later.

Cc: stable@vger.kernel.org
Reported-by: default avatarJulien Grall <julien@xen.org>
Fixes: b6622798 ("xen/events: avoid handling the same event on two cpus at the same time")
Tested-by: default avatarJulien Grall <julien@xen.org>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrvsky@oracle.com>
Link: https://lore.kernel.org/r/20210623130913.9405-1-jgross@suse.com


Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 107866a8

drivers/xen/events/events_base.c

+10 −1
Original line number Diff line number Diff line
@@ -642,6 +642,9 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious) 
	}



	info->eoi_time = 0;



	/* is_active hasn't been reset yet, do it now. */

	smp_store_release(&info->is_active, 0);

	do_unmask(info, EVT_MASK_REASON_EOI_PENDING);

}
@@ -811,6 +814,7 @@ static void xen_evtchn_close(evtchn_port_t port) 
		BUG();

}



/* Not called for lateeoi events. */

static void event_handler_exit(struct irq_info *info)

{

	smp_store_release(&info->is_active, 0);
@@ -1883,7 +1887,12 @@ static void lateeoi_ack_dynirq(struct irq_data *data) 


	if (VALID_EVTCHN(evtchn)) {

		do_mask(info, EVT_MASK_REASON_EOI_PENDING);

		event_handler_exit(info);

		/*

		 * Don't call event_handler_exit().

		 * Need to keep is_active non-zero in order to ignore re-raised

		 * events after cpu affinity changes while a lateeoi is pending.

		 */

		clear_evtchn(evtchn);

	}

}