Re: [PATCH v2 02/13] xen/pvcalls: connect to the backend
From: Boris Ostrovsky
Date: Wed Jul 26 2017 - 09:36:06 EST
On 7/25/2017 5:21 PM, Stefano Stabellini wrote:
Implement the probe function for the pvcalls frontend. Read the
supported versions, max-page-order and function-calls nodes from
xenstore.
Introduce a data structure named pvcalls_bedata. It contains pointers to
the command ring, the event channel, a list of active sockets and a list
of passive sockets. Lists accesses are protected by a spin_lock.
Introduce a waitqueue to allow waiting for a response on commands sent
to the backend.
Introduce an array of struct xen_pvcalls_response to store commands
responses.
Only one frontend<->backend connection is supported at any given time
for a guest. Store the active frontend device to a static pointer.
Introduce a stub functions for the event handler.
Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
CC: boris.ostrovsky@xxxxxxxxxx
CC: jgross@xxxxxxxx
---
drivers/xen/pvcalls-front.c | 153 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 153 insertions(+)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index a8d38c2..5e0b265 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -20,6 +20,29 @@
#include <xen/xenbus.h>
#include <xen/interface/io/pvcalls.h>
+#define PVCALLS_INVALID_ID (UINT_MAX)
Unnecessary parentheses
+#define RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
PVCALLS_RING_ORDER?
+#define PVCALLS_NR_REQ_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
+
+struct pvcalls_bedata {
+ struct xen_pvcalls_front_ring ring;
+ grant_ref_t ref;
+ int irq;
+
+ struct list_head socket_mappings;
+ struct list_head socketpass_mappings;
+ spinlock_t pvcallss_lock;
+
+ wait_queue_head_t inflight_req;
+ struct xen_pvcalls_response rsp[PVCALLS_NR_REQ_PER_RING];
+};
+struct xenbus_device *pvcalls_front_dev;
static
+
+static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
+{
+ return IRQ_HANDLED;
+}
+
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }
@@ -33,12 +56,142 @@ static int pvcalls_front_remove(struct xenbus_device *dev)
static int pvcalls_front_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
+ int ret = -EFAULT, evtchn, ref = -1, i;
+ unsigned int max_page_order, function_calls, len;
+ char *versions;
+ grant_ref_t gref_head = 0;
+ struct xenbus_transaction xbt;
+ struct pvcalls_bedata *bedata = NULL;
+ struct xen_pvcalls_sring *sring;
+
+ if (pvcalls_front_dev != NULL) {
+ dev_err(&dev->dev, "only one PV Calls connection supported\n");
+ return -EINVAL;
+ }
+
+ versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
+ if (!len)
+ return -EINVAL;
+ if (strcmp(versions, "1")) {
+ kfree(versions);
+ return -EINVAL;
+ }
+ kfree(versions);
+ ret = xenbus_scanf(XBT_NIL, dev->otherend,
+ "max-page-order", "%u", &max_page_order);
+ if (ret <= 0)
+ return -ENODEV;
+ if (max_page_order < RING_ORDER)
+ return -ENODEV;
+ ret = xenbus_scanf(XBT_NIL, dev->otherend,
+ "function-calls", "%u", &function_calls);
+ if (ret <= 0 || function_calls != 1)
+ return -ENODEV;
+ pr_info("%s max-page-order is %u\n", __func__, max_page_order);
+
+ bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
+ if (!bedata)
+ return -ENOMEM;
+
+ init_waitqueue_head(&bedata->inflight_req);
+ for (i = 0; i < PVCALLS_NR_REQ_PER_RING; i++)
+ bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
+
+ sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
+ __GFP_ZERO);
+ if (!sring)
+ goto error;
+ SHARED_RING_INIT(sring);
+ FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
+
+ ret = xenbus_alloc_evtchn(dev, &evtchn);
+ if (ret)
+ goto error;
+
+ bedata->irq = bind_evtchn_to_irqhandler(evtchn,
+ pvcalls_front_event_handler,
+ 0, "pvcalls-frontend", dev);
+ if (bedata->irq < 0) {
+ ret = bedata->irq;
+ goto error;
+ }
+
+ ret = gnttab_alloc_grant_references(1, &gref_head);
+ if (ret < 0)
+ goto error;
+ bedata->ref = ref = gnttab_claim_grant_reference(&gref_head);
Is ref really needed?
+ if (ref < 0)
+ goto error;
+ gnttab_grant_foreign_access_ref(ref, dev->otherend_id,
+ virt_to_gfn((void *)sring), 0);
+
+ 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, "ring-ref", "%d", ref);
+ if (ret)
+ goto error_xenbus;
+ ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
+ evtchn);
+ 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;
+ }
+
+ INIT_LIST_HEAD(&bedata->socket_mappings);
+ INIT_LIST_HEAD(&bedata->socketpass_mappings);
+ spin_lock_init(&bedata->pvcallss_lock);
+ dev_set_drvdata(&dev->dev, bedata);
+ pvcalls_front_dev = dev;
+ xenbus_switch_state(dev, XenbusStateInitialised);
+
return 0;
+
+ error_xenbus:
+ xenbus_transaction_end(xbt, 1);
+ xenbus_dev_fatal(dev, ret, "writing xenstore");
+ error:
+ pvcalls_front_remove(dev);
I think patch 12 (where you implement cleanup) could be moved before
this one.
I also think you are leaking bedata on error paths.
-boris
+ return ret;
}
static void pvcalls_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 pvcalls_front_driver = {