From 6f6f07b64cbe90e54f8e62b4d6f2404cf5306536 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 2 Oct 2020 08:37:35 +0200 Subject: [PATCH] evtchn/fifo: use stable fields when recording "last queue" information Both evtchn->priority and evtchn->notify_vcpu_id could change behind the back of evtchn_fifo_set_pending(), as for it - in the case of interdomain channels - only the remote side's per-channel lock is held. Neither the queue's priority nor the vCPU's vcpu_id fields have similar properties, so they seem better suited for the purpose. In particular they reflect the respective evtchn fields' values at the time they were used to determine queue and vCPU. Signed-off-by: Jan Beulich Reviewed-by: Julien Grall Reviewed-by: Paul Durrant --- xen/common/event_fifo.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/xen/common/event_fifo.c b/xen/common/event_fifo.c index 68d0c7a632..27ab3a1c3f 100644 --- a/xen/common/event_fifo.c +++ b/xen/common/event_fifo.c @@ -225,8 +225,8 @@ static void evtchn_fifo_set_pending(struct vcpu *v, struct evtchn *evtchn) /* Moved to a different queue? */ if ( old_q != q ) { - evtchn->last_vcpu_id = evtchn->notify_vcpu_id; - evtchn->last_priority = evtchn->priority; + evtchn->last_vcpu_id = v->vcpu_id; + evtchn->last_priority = q->priority; spin_unlock_irqrestore(&old_q->lock, flags); spin_lock_irqsave(&q->lock, flags); -- 2.39.5