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xen/events: reset active flag for lateeoi events later

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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: Julien Grall <julien@xen.org>
Fixes: b6622798bc ("xen/events: avoid handling the same event on two cpus at the same time")
Tested-by: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrvsky@oracle.com>
Link: https://lore.kernel.org/r/20210623130913.9405-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2021-06-23 15:09:13 +02:00
parent 107866a8eb
commit 3de218ff39
1 changed files with 10 additions and 1 deletions
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11
drivers/xen/events/events_base.c
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@ -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);
}
}