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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 4/7] xen/9pfs: connect to the backend
On 14/03/17 00:50, Stefano Stabellini wrote:
> Implement functions to handle the xenbus handshake. Upon connection,
> allocate the rings according to the protocol specification.
>
> Initialize a work_struct and a wait_queue. The work_struct will be used
> to schedule work upon receiving an event channel notification from the
> backend. The wait_queue will be used to wait when the ring is full and
> we need to send a new request.
>
> Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> CC: boris.ostrovsky@xxxxxxxxxx
> CC: jgross@xxxxxxxx
> CC: Eric Van Hensbergen <ericvh@xxxxxxxxx>
> CC: Ron Minnich <rminnich@xxxxxxxxxx>
> CC: Latchesar Ionkov <lucho@xxxxxxxxxx>
> CC: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx
> ---
> net/9p/trans_xen.c | 240
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 240 insertions(+)
>
> diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
> index f072876..974bac3 100644
> --- a/net/9p/trans_xen.c
> +++ b/net/9p/trans_xen.c
> @@ -41,6 +41,35 @@
> #include <net/9p/client.h>
> #include <net/9p/transport.h>
>
> +#define XEN_9PFS_NUM_RINGS 2
> +
> +/* One per ring, more than one per 9pfs share */
> +struct xen_9pfs_dataring {
> + struct xen_9pfs_front_priv *priv;
> +
> + struct xen_9pfs_data_intf *intf;
> + grant_ref_t ref;
> + int evtchn;
> + int irq;
> + spinlock_t lock;
> +
> + struct xen_9pfs_data data;
> + wait_queue_head_t wq;
> + struct work_struct work;
> +};
> +
> +/* One per 9pfs share */
> +struct xen_9pfs_front_priv {
> + struct list_head list;
> + struct xenbus_device *dev;
> + char *tag;
> + struct p9_client *client;
> +
> + int num_rings;
> + struct xen_9pfs_dataring *rings;
> +};
> +static LIST_HEAD(xen_9pfs_devs);
> +
> static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
> {
> return 0;
> @@ -60,6 +89,21 @@ static int p9_xen_request(struct p9_client *client, struct
> p9_req_t *p9_req)
> return 0;
> }
>
> +static void p9_xen_response(struct work_struct *work)
> +{
> +}
> +
> +static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
> +{
> + struct xen_9pfs_dataring *ring = r;
> + BUG_ON(!ring || !ring->priv->client);
> +
> + wake_up_interruptible(&ring->wq);
> + schedule_work(&ring->work);
> +
> + return IRQ_HANDLED;
> +}
> +
> static struct p9_trans_module p9_xen_trans = {
> .name = "xen",
> .maxsize = (1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT)),
> @@ -76,25 +120,221 @@ static int p9_xen_request(struct p9_client *client,
> struct p9_req_t *p9_req)
> { "" }
> };
>
> +static int xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
Return type void? You are always returning 0.
> +{
> + int i, j;
> +
> + list_del(&priv->list);
> +
> + for (i = 0; i < priv->num_rings; i++) {
> + if (priv->rings[i].intf == NULL)
> + break;
> + if (priv->rings[i].irq > 0)
> + unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
> + if (priv->rings[i].data.in != NULL) {
> + for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++)
> +
> gnttab_end_foreign_access(priv->rings[i].intf->ref[j], 0, 0);
> + free_pages((unsigned long)priv->rings[i].data.in,
> + XEN_9PFS_RING_ORDER - (PAGE_SHIFT -
> XEN_PAGE_SHIFT));
> + }
> + gnttab_end_foreign_access(priv->rings[i].ref, 0, 0);
> + free_page((unsigned long)priv->rings[i].intf);
> + }
> + kfree(priv->rings);
> + kfree(priv);
> +
> + return 0;
> +}
> +
> static int xen_9pfs_front_remove(struct xenbus_device *dev)
> {
> + int ret;
> + struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
> +
> + dev_set_drvdata(&dev->dev, NULL);
> + ret = xen_9pfs_front_free(priv);
> + return ret;
> +}
> +
> +static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
> + struct xen_9pfs_dataring *ring)
> +{
> + int i = 0;
> + int ret = -ENOMEM;
> + void *bytes = NULL;
> +
> + init_waitqueue_head(&ring->wq);
> + spin_lock_init(&ring->lock);
> + INIT_WORK(&ring->work, p9_xen_response);
> +
> + ring->intf = (struct xen_9pfs_data_intf *) get_zeroed_page(GFP_KERNEL |
> __GFP_ZERO);
I don't think you need __GFP_ZERO here.
> + if (!ring->intf)
> + return ret;
> + ret = ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
> + virt_to_gfn(ring->intf), 0);
> + if (ret < 0)
> + goto out;
> + bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
Coding style: (void *)
> + XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
> + if (bytes == NULL)
> + goto out;
> + for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
> + ret = ring->intf->ref[i] = gnttab_grant_foreign_access(
> + dev->otherend_id, virt_to_gfn(bytes) + i, 0);
> + if (ret < 0)
> + goto out;
> + }
> + ring->data.in = bytes;
> + ring->data.out = bytes + XEN_9PFS_RING_SIZE;
> +
> + ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
> + if (ret)
> + goto out;
> + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
> xen_9pfs_front_event_handler,
> + 0, "xen_9pfs-frontend", ring);
Did you think about using request_threaded_irq() instead of a workqueue?
For an example see e.g. drivers/scsi/xen-scsifront.c
> + if (ring->irq < 0) {
> + xenbus_free_evtchn(dev, ring->evtchn);
> + ret = ring->irq;
> + goto out;
> + }
> return 0;
> +
> +out:
> + if (bytes != NULL) {
> + for (i--; i >= 0; i--)
> + gnttab_end_foreign_access(ring->intf->ref[i], 0, 0);
> + free_pages((unsigned long)bytes,
> + XEN_9PFS_RING_ORDER - (PAGE_SHIFT -
> XEN_PAGE_SHIFT));
> + }
> + gnttab_end_foreign_access(ring->ref, 0, 0);
> + free_page((unsigned long)ring->intf);
> + return ret;
> }
>
> static int xen_9pfs_front_probe(struct xenbus_device *dev,
> const struct xenbus_device_id *id)
> {
> + int ret, i;
> + struct xenbus_transaction xbt;
> + struct xen_9pfs_front_priv *priv = NULL;
> + char *versions;
> + unsigned int max_rings, max_ring_order, len;
> +
> + versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
> + if (!len || strcmp(versions, "1"))
You are leaking versions in case of not being "1".
Can't you use xenbus_read_unsigned() instead of xenbus_read()?
> + return -EINVAL;
> + kfree(versions);
> + ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-rings", "%u",
> &max_rings);
xenbus_read_unsigned()?
> + if (ret < 0 || max_rings < XEN_9PFS_NUM_RINGS)
> + return -EINVAL;
> + ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-ring-page-order", "%u",
> &max_ring_order);
xenbus_read_unsigned()
> + if (ret < 0|| max_ring_order < XEN_9PFS_RING_ORDER)
Coding style (missing space before ||)
> + return -EINVAL;
> +
> +
> + priv = kzalloc(sizeof(struct xen_9pfs_front_priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->dev = dev;
> + priv->num_rings = XEN_9PFS_NUM_RINGS;
> + priv->rings = kzalloc(sizeof(struct xen_9pfs_dataring) *
> priv->num_rings,
> + GFP_KERNEL);
Coding style: please align the second line to the first parameter of
kzalloc().
> + if (!priv->rings) {
> + kfree(priv);
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < priv->num_rings; i++) {
> + priv->rings[i].priv = priv;
> + ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]);
> + if (ret < 0)
> + goto error;
> + }
> +
> + again:
> + ret = xenbus_transaction_start(&xbt);
> + if (ret) {
> + xenbus_dev_fatal(dev, ret, "starting transaction");
> + goto error;
> + }
> + ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
> + if (ret)
> + goto error_xenbus;
> + ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
> priv->num_rings);
> + if (ret)
> + goto error_xenbus;
> + for (i = 0; i < priv->num_rings; i++) {
> + char str[16];
> +
> + sprintf(str, "ring-ref%u", i);
> + ret = xenbus_printf(xbt, dev->nodename, str, "%d",
> priv->rings[i].ref);
> + if (ret)
> + goto error_xenbus;
> +
> + sprintf(str, "event-channel-%u", i);
This is dangerous: you are hard coding num_rings always being less than
10 here. Otherwise str[] isn't large enough. Mind adding
BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9)?
> + ret = xenbus_printf(xbt, dev->nodename, str, "%u",
> priv->rings[i].evtchn);
> + if (ret)
> + goto error_xenbus;
> + }
> + priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
> + if (ret)
> + goto error_xenbus;
> + ret = xenbus_transaction_end(xbt, 0);
> + if (ret) {
> + if (ret == -EAGAIN)
> + goto again;
> + xenbus_dev_fatal(dev, ret, "completing transaction");
> + goto error;
> + }
> +
> + list_add_tail(&priv->list, &xen_9pfs_devs);
Don't you need some kind of lock protecting the list?
> + dev_set_drvdata(&dev->dev, priv);
> + xenbus_switch_state(dev, XenbusStateInitialised);
> +
> return 0;
> +
> + error_xenbus:
> + xenbus_transaction_end(xbt, 1);
> + xenbus_dev_fatal(dev, ret, "writing xenstore");
> + error:
> + dev_set_drvdata(&dev->dev, NULL);
> + xen_9pfs_front_free(priv);
> + return ret;
> }
>
> static int xen_9pfs_front_resume(struct xenbus_device *dev)
> {
> + dev_warn(&dev->dev, "suspsend/resume unsupported\n");
> return 0;
> }
>
> static void xen_9pfs_front_changed(struct xenbus_device *dev,
> enum xenbus_state backend_state)
> {
> + switch (backend_state) {
> + case XenbusStateReconfiguring:
> + case XenbusStateReconfigured:
> + case XenbusStateInitialising:
> + case XenbusStateInitialised:
> + case XenbusStateUnknown:
> + break;
> +
> + case XenbusStateInitWait:
> + break;
> +
> + case XenbusStateConnected:
> + xenbus_switch_state(dev, XenbusStateConnected);
> + break;
> +
> + case XenbusStateClosed:
> + if (dev->state == XenbusStateClosed)
> + break;
> + /* Missed the backend's CLOSING state -- fallthrough */
> + case XenbusStateClosing:
> + xenbus_frontend_closed(dev);
> + break;
> + }
> }
>
> static struct xenbus_driver xen_9pfs_front_driver = {
>
Juergen
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