From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH v7 2/3] tcm_vhost: Add helper to check if endpoint is setup Date: Thu, 18 Apr 2013 10:09:53 +0300 Message-ID: <20130418070953.GD13787@redhat.com> References: <20130417131726.GA26157@redhat.com> <1366247154-3136-3-git-send-email-asias@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1366247154-3136-3-git-send-email-asias@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Asias He Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, Stefan Hajnoczi , Paolo Bonzini List-Id: virtualization@lists.linuxfoundation.org On Thu, Apr 18, 2013 at 09:05:53AM +0800, Asias He wrote: > Signed-off-by: Asias He > --- > drivers/vhost/tcm_vhost.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c > index 88ebb79..8f05528 100644 > --- a/drivers/vhost/tcm_vhost.c > +++ b/drivers/vhost/tcm_vhost.c > @@ -111,6 +111,24 @@ static bool tcm_vhost_check_feature(struct vhost_scsi *vs, int feature) > return ret; > } > > +static bool tcm_vhost_check_endpoint(struct vhost_virtqueue *vq) > +{ > + bool ret = false; > + > + /* > + * We can handle the vq only after the endpoint is setup by calling the > + * VHOST_SCSI_SET_ENDPOINT ioctl. > + * > + * TODO: Check that we are running from vhost_worker which acts > + * as read-side critical section for vhost kind of RCU. > + * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h > + */ > + if (rcu_dereference_check(vq->private_data, 1)) > + ret = true; > + > + return ret; > +} > + You can't use RCU in this way. You need to actually derefence. Instead, just move this within vq mutex and do rcu_dereference_protected. document that this function requires vq mutex. > static int tcm_vhost_check_true(struct se_portal_group *se_tpg) > { > return 1; > -- > 1.8.1.4