Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754618Ab0F0JEk (ORCPT ); Sun, 27 Jun 2010 05:04:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24217 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752701Ab0F0JEh (ORCPT ); Sun, 27 Jun 2010 05:04:37 -0400 Date: Sun, 27 Jun 2010 11:59:07 +0300 From: "Michael S. Tsirkin" To: Sridhar Samudrala , Arnd Bergmann , "Paul E. McKenney" , Juan Quintela , Rusty Russell , Jes.Sorensen@redhat.com, kraxel@redhat.com, Takuya Yoshikawa , kvm@vger.kernel.org, virtualization@lists.osdl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] vhost: break out of polling loop on error Message-ID: <20100627085907.GA8588@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7283 Lines: 196 When ring parsing fails, we currently handle this as ring empty condition. This means that we enable kicks and recheck ring empty: if this not empty, we re-start polling which of course will fail again. Instead, let's return a negative error code and stop polling. Signed-off-by: Michael S. Tsirkin --- Dave, I'm sending this out so it can get reviewed. I'll put this on my vhost tree so no need for you to pick this patch directly. drivers/vhost/net.c | 12 ++++++++++-- drivers/vhost/vhost.c | 33 +++++++++++++++++---------------- drivers/vhost/vhost.h | 8 ++++---- 3 files changed, 31 insertions(+), 22 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 0f41c91..54096ee 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -98,7 +98,8 @@ static void tx_poll_start(struct vhost_net *net, struct socket *sock) static void handle_tx(struct vhost_net *net) { struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX]; - unsigned head, out, in, s; + unsigned out, in, s; + int head; struct msghdr msg = { .msg_name = NULL, .msg_namelen = 0, @@ -135,6 +136,9 @@ static void handle_tx(struct vhost_net *net) ARRAY_SIZE(vq->iov), &out, &in, NULL, NULL); + /* On error, stop handling until the next kick. */ + if (head < 0) + break; /* Nothing new? Wait for eventfd to tell us they refilled. */ if (head == vq->num) { wmem = atomic_read(&sock->sk->sk_wmem_alloc); @@ -192,7 +196,8 @@ static void handle_tx(struct vhost_net *net) static void handle_rx(struct vhost_net *net) { struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX]; - unsigned head, out, in, log, s; + unsigned out, in, log, s; + int head; struct vhost_log *vq_log; struct msghdr msg = { .msg_name = NULL, @@ -228,6 +233,9 @@ static void handle_rx(struct vhost_net *net) ARRAY_SIZE(vq->iov), &out, &in, vq_log, &log); + /* On error, stop handling until the next kick. */ + if (head < 0) + break; /* OK, now we need to know about added descriptors. */ if (head == vq->num) { if (unlikely(vhost_enable_notify(vq))) { diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 3b83382..5ccd384 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -873,12 +873,13 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, * number of output then some number of input descriptors, it's actually two * iovecs, but we pack them into one and note how many of each there were. * - * This function returns the descriptor number found, or vq->num (which - * is never a valid descriptor number) if none was found. */ -unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, - struct iovec iov[], unsigned int iov_size, - unsigned int *out_num, unsigned int *in_num, - struct vhost_log *log, unsigned int *log_num) + * This function returns the descriptor number found, or vq->num (which is + * never a valid descriptor number) if none was found. A negative code is + * returned on error. */ +int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, + struct iovec iov[], unsigned int iov_size, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num) { struct vring_desc desc; unsigned int i, head, found = 0; @@ -890,13 +891,13 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, if (get_user(vq->avail_idx, &vq->avail->idx)) { vq_err(vq, "Failed to access avail idx at %p\n", &vq->avail->idx); - return vq->num; + return -EFAULT; } if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) { vq_err(vq, "Guest moved used index from %u to %u", last_avail_idx, vq->avail_idx); - return vq->num; + return -EFAULT; } /* If there's nothing new since last we looked, return invalid. */ @@ -912,14 +913,14 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, vq_err(vq, "Failed to read head: idx %d address %p\n", last_avail_idx, &vq->avail->ring[last_avail_idx % vq->num]); - return vq->num; + return -EFAULT; } /* If their number is silly, that's an error. */ if (head >= vq->num) { vq_err(vq, "Guest says index %u > %u is available", head, vq->num); - return vq->num; + return -EINVAL; } /* When we start there are none of either input nor output. */ @@ -933,19 +934,19 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, if (i >= vq->num) { vq_err(vq, "Desc index is %u > %u, head = %u", i, vq->num, head); - return vq->num; + return -EINVAL; } if (++found > vq->num) { vq_err(vq, "Loop detected: last one at %u " "vq size %u head %u\n", i, vq->num, head); - return vq->num; + return -EINVAL; } ret = copy_from_user(&desc, vq->desc + i, sizeof desc); if (ret) { vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", i, vq->desc + i); - return vq->num; + return -EFAULT; } if (desc.flags & VRING_DESC_F_INDIRECT) { ret = get_indirect(dev, vq, iov, iov_size, @@ -954,7 +955,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, if (ret < 0) { vq_err(vq, "Failure detected " "in indirect descriptor at idx %d\n", i); - return vq->num; + return ret; } continue; } @@ -964,7 +965,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, if (ret < 0) { vq_err(vq, "Translation failure %d descriptor idx %d\n", ret, i); - return vq->num; + return ret; } if (desc.flags & VRING_DESC_F_WRITE) { /* If this is an input descriptor, @@ -981,7 +982,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, if (*in_num) { vq_err(vq, "Descriptor has out after in: " "idx %d\n", i); - return vq->num; + return -EINVAL; } *out_num += ret; } diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 44591ba..11ee13d 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -120,10 +120,10 @@ long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg); int vhost_vq_access_ok(struct vhost_virtqueue *vq); int vhost_log_access_ok(struct vhost_dev *); -unsigned vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *, - struct iovec iov[], unsigned int iov_count, - unsigned int *out_num, unsigned int *in_num, - struct vhost_log *log, unsigned int *log_num); +int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *, + struct iovec iov[], unsigned int iov_count, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num); void vhost_discard_vq_desc(struct vhost_virtqueue *); int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len); -- 1.7.1.12.g42b7f -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/