[PATCH 3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup()

David Woodhouse
2020-10-27T13:55:32Z

From: David Woodhouse <dwmw@amazon.co.uk>

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>
---
virt/kvm/eventfd.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index d6408bb497dc..98b5cfa1d69f 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);
--
2.26.2