From: David Woodhouse <dwmw@amazon.co.uk>
Date: Tue, 27 Oct 2020 13:43:46 +0000 (+0000)
Subject: kvm/eventfd: Drain events from eventfd in irqfd_wakeup()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=6703ffb9553e36fe0ebc0f9d3aa03f45ad22187b;p=users%2Fdwmw2%2Flinux.git

kvm/eventfd: Drain events from eventfd in irqfd_wakeup()

Don't allow the events to accumulate in the eventfd counter, drain them
as they are handled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index c2323c27a28b5..2b93893657fc9 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -193,6 +193,9 @@ irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 	int idx;
 
 	if (flags & EPOLLIN) {
+		u64 cnt;
+		eventfd_ctx_do_read(irqfd->eventfd, &cnt);
+
 		idx = srcu_read_lock(&kvm->irq_srcu);
 		do {
 			seq = read_seqcount_begin(&irqfd->irq_entry_sc);