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Subject[PATCH v7 12/13] xen/pvcalls: implement release command
Date
Send PVCALLS_RELEASE to the backend and wait for a reply. Take both
in_mutex and out_mutex to avoid concurrent accesses. Then, free the
socket.

For passive sockets, check whether we have already pre-allocated an
active socket for the purpose of being accepted. If so, free that as
well.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
drivers/xen/pvcalls-front.c | 98 +++++++++++++++++++++++++++++++++++++++++++++
drivers/xen/pvcalls-front.h | 1 +
2 files changed, 99 insertions(+)

diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index eab70ce..8e7426083 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -199,6 +199,21 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
struct sock_mapping *map)
{
+ int i;
+
+ unbind_from_irqhandler(map->active.irq, map);
+
+ spin_lock(&bedata->socket_lock);
+ if (!list_empty(&map->list))
+ list_del_init(&map->list);
+ spin_unlock(&bedata->socket_lock);
+
+ for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
+ gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
+ gnttab_end_foreign_access(map->active.ref, 0, 0);
+ free_page((unsigned long)map->active.ring);
+
+ kfree(map);
}

static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
@@ -966,6 +981,89 @@ unsigned int pvcalls_front_poll(struct file *file, struct socket *sock,
return ret;
}

+int pvcalls_front_release(struct socket *sock)
+{
+ struct pvcalls_bedata *bedata;
+ struct sock_mapping *map;
+ int req_id, notify, ret;
+ struct xen_pvcalls_request *req;
+
+ if (sock->sk == NULL)
+ return 0;
+
+ pvcalls_enter();
+ if (!pvcalls_front_dev) {
+ pvcalls_exit();
+ return -EIO;
+ }
+
+ bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
+
+ map = (struct sock_mapping *) sock->sk->sk_send_head;
+ if (map == NULL) {
+ pvcalls_exit();
+ return 0;
+ }
+
+ spin_lock(&bedata->socket_lock);
+ ret = get_request(bedata, &req_id);
+ if (ret < 0) {
+ spin_unlock(&bedata->socket_lock);
+ pvcalls_exit();
+ return ret;
+ }
+ sock->sk->sk_send_head = NULL;
+
+ req = RING_GET_REQUEST(&bedata->ring, req_id);
+ req->req_id = req_id;
+ req->cmd = PVCALLS_RELEASE;
+ req->u.release.id = (uint64_t)map;
+
+ bedata->ring.req_prod_pvt++;
+ RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
+ spin_unlock(&bedata->socket_lock);
+ if (notify)
+ notify_remote_via_irq(bedata->irq);
+
+ wait_event(bedata->inflight_req,
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+
+ if (map->active_socket) {
+ /*
+ * Set in_error and wake up inflight_conn_req to force
+ * recvmsg waiters to exit.
+ */
+ map->active.ring->in_error = -EBADF;
+ wake_up_interruptible(&map->active.inflight_conn_req);
+
+ /*
+ * Wait until there are no more waiters on the mutexes.
+ * We know that no new waiters can be added because sk_send_head
+ * is set to NULL -- we only need to wait for the existing
+ * waiters to return.
+ */
+ while (!mutex_trylock(&map->active.in_mutex) ||
+ !mutex_trylock(&map->active.out_mutex))
+ cpu_relax();
+
+ pvcalls_front_free_map(bedata, map);
+ } else {
+ spin_lock(&bedata->socket_lock);
+ list_del(&map->list);
+ spin_unlock(&bedata->socket_lock);
+ if (READ_ONCE(map->passive.inflight_req_id) !=
+ PVCALLS_INVALID_ID) {
+ pvcalls_front_free_map(bedata,
+ map->passive.accept_map);
+ }
+ kfree(map);
+ }
+ WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
+
+ pvcalls_exit();
+ return 0;
+}
+
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }
diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h
index 25e05b8..3332978 100644
--- a/drivers/xen/pvcalls-front.h
+++ b/drivers/xen/pvcalls-front.h
@@ -23,5 +23,6 @@ int pvcalls_front_recvmsg(struct socket *sock,
unsigned int pvcalls_front_poll(struct file *file,
struct socket *sock,
poll_table *wait);
+int pvcalls_front_release(struct socket *sock);

#endif
--
1.9.1
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