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Merge tag 'for-linus-5.13b-rc8-tag' of git://git.kernel.org/pub/scm/l…
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…inux/kernel/git/xen/tip

Pull xen fix from Juergen Gross:
 "A fix for a regression introduced in 5.12: when migrating an irq
  related to a Xen user event to another cpu, a race might result
  in a WARN() triggering"

* tag 'for-linus-5.13b-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/events: reset active flag for lateeoi events later
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torvalds committed Jun 25, 2021
2 parents 616a99d + 3de218f commit b960e01
Showing 1 changed file with 10 additions and 1 deletion.
11 changes: 10 additions & 1 deletion drivers/xen/events/events_base.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
}
}

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