From 526d3e7ff515582eaf7cf5d9da2a11bf681204e6 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 4 Mar 2016 06:24:51 -0500 Subject: [PATCH] vhost: introduce vhost_has_work() This path introduces a helper which can give a hint for whether or not there's a work queued in the work list. This could be used for busy polling code to exit the busy loop. Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 7 +++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 8 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 328c54ab0154..596de212fe7e 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -263,6 +263,13 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) } EXPORT_SYMBOL_GPL(vhost_work_queue); +/* A lockless hint for busy polling code to exit the loop */ +bool vhost_has_work(struct vhost_dev *dev) +{ + return !list_empty(&dev->work_list); +} +EXPORT_SYMBOL_GPL(vhost_has_work); + void vhost_poll_queue(struct vhost_poll *poll) { vhost_work_queue(poll->dev, &poll->work); diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 8f0dd0d915d4..eef33b11a7ed 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -37,6 +37,7 @@ struct vhost_poll { void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn); void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work); +bool vhost_has_work(struct vhost_dev *dev); void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, unsigned long mask, struct vhost_dev *dev); -- 2.20.1