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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v5 4/7] xen/9pfs: connect to the backend
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: groug@xxxxxxxx
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 | 273 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 273 insertions(+)
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 3d07260..5279ae0 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -37,10 +37,46 @@
#include <xen/interface/io/9pfs.h>
#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/rwlock.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
+#define XEN_9PFS_NUM_RINGS 2
+#define XEN_9PFS_RING_ORDER 6
+#define XEN_9PFS_RING_SIZE XEN_FLEX_RING_SIZE(XEN_9PFS_RING_ORDER)
+
+/* 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;
+ /* protect a ring from concurrent accesses */
+ 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 DEFINE_RWLOCK(xen_9pfs_lock);
+
static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
{
return 0;
@@ -60,6 +96,25 @@ 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;
+
+ if (!ring || !ring->priv->client) {
+ /* ignore spurious interrupt */
+ return IRQ_HANDLED;
+ }
+
+ 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 +131,243 @@ static int p9_xen_request(struct p9_client *client,
struct p9_req_t *p9_req)
{ "" }
};
+static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
+{
+ int i, j;
+
+ write_lock(&xen_9pfs_lock);
+ list_del(&priv->list);
+ write_unlock(&xen_9pfs_lock);
+
+ for (i = 0; i < priv->num_rings; i++) {
+ if (!priv->rings[i].intf)
+ break;
+ if (priv->rings[i].irq > 0)
+ unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
+ if (priv->rings[i].data.in) {
+ for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) {
+ grant_ref_t ref;
+
+ ref = priv->rings[i].intf->ref[j];
+ gnttab_end_foreign_access(ref, 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->tag);
+ kfree(priv);
+}
+
static int xen_9pfs_front_remove(struct xenbus_device *dev)
{
+ struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
+
+ dev_set_drvdata(&dev->dev, NULL);
+ xen_9pfs_front_free(priv);
+ return 0;
+}
+
+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);
+ if (!ring->intf)
+ return ret;
+ ret = gnttab_grant_foreign_access(dev->otherend_id,
+ virt_to_gfn(ring->intf), 0);
+ if (ret < 0)
+ goto out;
+ ring->ref = ret;
+ bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT));
+ if (!bytes)
+ goto out;
+ for (; i < (1 << XEN_9PFS_RING_ORDER); i++) {
+ ret = gnttab_grant_foreign_access(
+ dev->otherend_id, virt_to_gfn(bytes) + i, 0);
+ if (ret < 0)
+ goto out;
+ ring->intf->ref[i] = ret;
+ }
+ ring->intf->ring_order = XEN_9PFS_RING_ORDER;
+ 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);
+ if (ring->irq < 0) {
+ xenbus_free_evtchn(dev, ring->evtchn);
+ ret = ring->irq;
+ goto out;
+ }
return 0;
+
+out:
+ if (!bytes) {
+ 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)
+ return -EINVAL;
+ if (strcmp(versions, "1")) {
+ kfree(versions);
+ return -EINVAL;
+ }
+ kfree(versions);
+ max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
+ if (max_rings < XEN_9PFS_NUM_RINGS)
+ return -EINVAL;
+ max_ring_order = xenbus_read_unsigned(dev->otherend,
+ "max-ring-page-order", 0);
+ if (max_ring_order < XEN_9PFS_RING_ORDER)
+ return -EINVAL;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->dev = dev;
+ priv->num_rings = XEN_9PFS_NUM_RINGS;
+ priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
+ GFP_KERNEL);
+ 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];
+
+ BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
+ 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);
+ 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 (!priv->tag) {
+ ret = -EINVAL;
+ 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;
+ }
+
+ write_lock(&xen_9pfs_lock);
+ list_add_tail(&priv->list, &xen_9pfs_devs);
+ write_unlock(&xen_9pfs_lock);
+ 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 = {
--
1.9.1
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