Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924AbcCDLZQ (ORCPT ); Fri, 4 Mar 2016 06:25:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50915 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751112AbcCDLZN (ORCPT ); Fri, 4 Mar 2016 06:25:13 -0500 From: Jason Wang To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: RAPOPORT@il.ibm.com, yang.zhang.wz@gmail.com, borntraeger@de.ibm.com, Jason Wang Subject: [PATCH V4 1/3] vhost: introduce vhost_has_work() Date: Fri, 4 Mar 2016 06:24:51 -0500 Message-Id: <1457090693-55974-2-git-send-email-jasowang@redhat.com> In-Reply-To: <1457090693-55974-1-git-send-email-jasowang@redhat.com> References: <1457090693-55974-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1393 Lines: 42 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 --- 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 ad2146a..90ac092 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -245,6 +245,13 @@ 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 d3f7674..43284ad 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); -- 1.8.3.1