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Commit 52f44e0d authored by Venkateswararao Jujjuri (JV)'s avatar Venkateswararao Jujjuri (JV) Committed by Eric Van Hensbergen
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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: default avatarVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 419b3956

net/9p/client.c

+2 −1
Original line number Diff line number Diff line
@@ -583,6 +583,7 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...) 


	err = c->trans_mod->request(c, req);

	if (err < 0) {

		if (err != -ERESTARTSYS)

			c->status = Disconnected;

		goto reterr;

	}

net/9p/trans_virtio.c

+39 −7
Original line number Diff line number Diff line
@@ -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);
@@ -222,11 +231,24 @@ 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) {

		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");

					"9p debug: "

					"virtio rpc add_buf returned failure");

			return -EIO;

		}

	}



	virtqueue_kick(chan->vq);

	spin_unlock_irqrestore(&chan->lock, flags);
@@ -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);



}