[PATCH 2/3] vfio/virqfd: Drain events from eventfd in virqfd_wakeup()

David Woodhouse
2020-10-27T13:55:49Z

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>
---
drivers/vfio/virqfd.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/vfio/virqfd.c b/drivers/vfio/virqfd.c
index 997cb5d0a657..414e98d82b02 100644
--- a/drivers/vfio/virqfd.c
+++ b/drivers/vfio/virqfd.c
@@ -46,6 +46,9 @@ static int virqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void
__poll_t flags = key_to_poll(key);

if (flags & EPOLLIN) {
+ u64 cnt;
+ eventfd_ctx_do_read(virqfd->eventfd, &cnt);
+
/* An event has been signaled, call function */
if ((!virqfd->handler ||
virqfd->handler(virqfd->opaque, virqfd->data)) &&
--
2.26.2