From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38682) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmi1N-0003Y7-Vx for qemu-devel@nongnu.org; Tue, 29 Aug 2017 11:01:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmi1K-0006yV-3x for qemu-devel@nongnu.org; Tue, 29 Aug 2017 11:01:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46726) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dmi1J-0006yH-Qj for qemu-devel@nongnu.org; Tue, 29 Aug 2017 11:01:38 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 73CA691FC3 for ; Tue, 29 Aug 2017 15:01:36 +0000 (UTC) Date: Tue, 29 Aug 2017 18:01:30 +0300 From: "Michael S. Tsirkin" Message-ID: <20170829175820-mutt-send-email-mst@kernel.org> References: <20170829144805.28872-1-marcandre.lureau@redhat.com> <20170829144805.28872-2-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20170829144805.28872-2-marcandre.lureau@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 1/2] libvhost-user: support resuming vq->last_avail_idx based on used_idx List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?iso-8859-1?Q?Marc-Andr=E9?= Lureau Cc: qemu-devel@nongnu.org, victork@redhat.com On Tue, Aug 29, 2017 at 04:48:04PM +0200, Marc-Andr=E9 Lureau wrote: > This is the same workaround as commit 523b018dde3b765, which was lost > with libvhost-user transition in commit e10e798c85c2331. >=20 > Signed-off-by: Marc-Andr=E9 Lureau > --- > contrib/libvhost-user/libvhost-user.h | 5 +++++ > contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++ > 2 files changed, 18 insertions(+) >=20 > diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-u= ser/libvhost-user.h > index 53ef222c0b..aca71717c1 100644 > --- a/contrib/libvhost-user/libvhost-user.h > +++ b/contrib/libvhost-user/libvhost-user.h > @@ -132,6 +132,7 @@ typedef void (*vu_set_features_cb) (VuDev *dev, uin= t64_t features); > typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg, > int *do_reply); > typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool st= arted); > +typedef bool (*vu_queue_resume_to_used_cb) (VuDev *dev, int qidx); > =20 > typedef struct VuDevIface { > /* called by VHOST_USER_GET_FEATURES to get the features bitmask *= / > @@ -148,6 +149,10 @@ typedef struct VuDevIface { > vu_process_msg_cb process_msg; > /* tells when queues can be processed */ > vu_queue_set_started_cb queue_set_started; > + /* If the queue must be resumed to vring.used->idx. */ > + /* This can help to support resuming on unmanaged exit/crash when > + * the slave/driver processes elements in order. */ > + vu_queue_resume_to_used_cb queue_resume_to_used; > } VuDevIface; > =20 > typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx); Let's consider: this is only safe if queue is processed in order. So I think that would be a better name for the field. > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-u= ser/libvhost-user.c > index 35fa0c5e56..36439caed6 100644 > --- a/contrib/libvhost-user/libvhost-user.c > +++ b/contrib/libvhost-user/libvhost-user.c > @@ -521,6 +521,19 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *v= msg) > =20 > vq->used_idx =3D vq->vring.used->idx; > =20 > + if (vq->last_avail_idx !=3D vq->used_idx) { > + bool resume =3D dev->iface->queue_resume_to_used && > + dev->iface->queue_resume_to_used(dev, index); > + > + DPRINT("Last avail index !=3D used index: %u !=3D %u%s\n", > + vq->last_avail_idx, vq->used_idx, > + resume ? ", resuming" : ""); > + > + if (resume) { > + vq->shadow_avail_idx =3D vq->last_avail_idx =3D vq->used_i= dx; > + } > + } > + > return false; > } > =20 > --=20 > 2.14.1.146.gd35faa819