From 52f44e0d08ff1a065bf06615483c608163575cb1 Mon Sep 17 00:00:00 2001 From: "Venkateswararao Jujjuri (JV)" Date: Wed, 29 Sep 2010 18:33:41 -0700 Subject: net/9p: Add waitq to VirtIO transport. If there is not enough space for the PDU on the VirtIO ring, current code returns -EIO propagating the error to user. This patch introduced a wqit_queue on the channel, and lets the process wait on this queue until VirtIO ring frees up. Signed-off-by: Venkateswararao Jujjuri Signed-off-by: Eric Van Hensbergen --- net/9p/client.c | 3 ++- net/9p/trans_virtio.c | 46 +++++++++++++++++++++++++++++++++++++++------- 2 files changed, 41 insertions(+), 8 deletions(-) (limited to 'net') diff --git a/net/9p/client.c b/net/9p/client.c index 2bc99e9031e7..bc7b03537699 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -583,7 +583,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...) err = c->trans_mod->request(c, req); if (err < 0) { - c->status = Disconnected; + if (err != -ERESTARTSYS) + c->status = Disconnected; goto reterr; } diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 8ae08596aad8..c8f3f72ab20e 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -75,6 +75,8 @@ struct virtio_chan { struct p9_client *client; struct virtio_device *vdev; struct virtqueue *vq; + int ring_bufs_avail; + wait_queue_head_t *vc_wq; /* Scatterlist: can be too big for stack. */ struct scatterlist sg[VIRTQUEUE_NUM]; @@ -141,15 +143,21 @@ static void req_done(struct virtqueue *vq) do { spin_lock_irqsave(&chan->lock, flags); rc = virtqueue_get_buf(chan->vq, &len); - spin_unlock_irqrestore(&chan->lock, flags); if (rc != NULL) { + if (!chan->ring_bufs_avail) { + chan->ring_bufs_avail = 1; + wake_up(chan->vc_wq); + } + spin_unlock_irqrestore(&chan->lock, flags); P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); req = p9_tag_lookup(chan->client, rc->tag); req->status = REQ_STATUS_RCVD; p9_client_cb(chan->client, req); + } else { + spin_unlock_irqrestore(&chan->lock, flags); } } while (rc != NULL); } @@ -212,6 +220,7 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req) P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n"); +req_retry: req->status = REQ_STATUS_SENT; spin_lock_irqsave(&chan->lock, flags); @@ -222,10 +231,23 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req) err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc); if (err < 0) { - spin_unlock_irqrestore(&chan->lock, flags); - P9_DPRINTK(P9_DEBUG_TRANS, - "9p debug: virtio rpc add_buf returned failure"); - return -EIO; + if (err == -ENOSPC) { + chan->ring_bufs_avail = 0; + spin_unlock_irqrestore(&chan->lock, flags); + err = wait_event_interruptible(*chan->vc_wq, + chan->ring_bufs_avail); + if (err == -ERESTARTSYS) + return err; + + P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n"); + goto req_retry; + } else { + spin_unlock_irqrestore(&chan->lock, flags); + P9_DPRINTK(P9_DEBUG_TRANS, + "9p debug: " + "virtio rpc add_buf returned failure"); + return -EIO; + } } virtqueue_kick(chan->vq); @@ -304,14 +326,23 @@ static int p9_virtio_probe(struct virtio_device *vdev) chan->tag_len = tag_len; err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); if (err) { - kfree(tag); - goto out_free_vq; + goto out_free_tag; } + chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); + if (!chan->vc_wq) { + err = -ENOMEM; + goto out_free_tag; + } + init_waitqueue_head(chan->vc_wq); + chan->ring_bufs_avail = 1; + mutex_lock(&virtio_9p_lock); list_add_tail(&chan->chan_list, &virtio_chan_list); mutex_unlock(&virtio_9p_lock); return 0; +out_free_tag: + kfree(tag); out_free_vq: vdev->config->del_vqs(vdev); kfree(chan); @@ -385,6 +416,7 @@ static void p9_virtio_remove(struct virtio_device *vdev) mutex_unlock(&virtio_9p_lock); sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); kfree(chan->tag); + kfree(chan->vc_wq); kfree(chan); } -- cgit v1.2.3-59-g8ed1b