drivers/xen/events/events_base.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
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.
Reported-by: Julien Grall <julien@xen.org>
Fixes: b6622798bc50b62 ("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>
---
drivers/xen/events/events_base.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 7bbfd58958bc..d7e361fb0548 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -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);
}
}
--
2.26.2
On 6/23/21 9:09 AM, Juergen Gross wrote: > 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. > > Reported-by: Julien Grall <julien@xen.org> > Fixes: b6622798bc50b62 ("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>
On 2021-06-23 14:09, Juergen Gross wrote: > 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. > > Reported-by: Julien Grall <julien@xen.org> > Fixes: b6622798bc50b62 ("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> > --- Hi Juergen, Are you planning on backporting this fix to releases <= 5.10? I think the fix may need some minor adjustment to make it work after "xen/events: fix setting irq affinity" since both lateeoi_ack_dynirq() and lateeoi_mask_ack_dynirq() were adjusted to call ack_dynirq(). Thanks, Ross
On 05.07.21 11:00, Ross Lagerwall wrote: > On 2021-06-23 14:09, Juergen Gross wrote: >> 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. >> >> Reported-by: Julien Grall <julien@xen.org> >> Fixes: b6622798bc50b62 ("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> >> --- > > Hi Juergen, > > Are you planning on backporting this fix to releases <= 5.10? It is on my todo list. :-) Juergen
© 2016 - 2024 Red Hat, Inc.