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net/9p: Add waitq to VirtIO transport.

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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 <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
Venkateswararao Jujjuri (JV) 2010-09-29 18:33:41 -07:00 committed by Eric Van Hensbergen
parent 419b39561e
commit 52f44e0d08
2 changed files with 41 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
net/9p/client.c
View File

@ -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;
}

46
net/9p/trans_virtio.c
View File

@ -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);
}