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Date: Fri, 21 Jul 2017 17:11:57 -0700
From: Stefano Stabellini <sstabellini@...nel.org>
To: xen-devel@...ts.xen.org
Cc: linux-kernel@...r.kernel.org, sstabellini@...nel.org,
jgross@...e.com, boris.ostrovsky@...cle.com,
Stefano Stabellini <stefano@...reto.com>
Subject: [PATCH v1 07/13] xen/pvcalls: implement accept command
Send PVCALLS_ACCEPT to the backend. Allocate a new active socket. Make
sure that only one accept command is executed at any given time by
setting PVCALLS_FLAG_ACCEPT_INFLIGHT and waiting on the
inflight_accept_req waitqueue.
sock->sk->sk_send_head is not used for ip sockets: reuse the field to
store a pointer to the struct sock_mapping corresponding to the socket.
Convert the new struct socket pointer into an uint64_t and use it as id
for the new socket to pass to the backend.
Signed-off-by: Stefano Stabellini <stefano@...reto.com>
CC: boris.ostrovsky@...cle.com
CC: jgross@...e.com
---
drivers/xen/pvcalls-front.c | 79 +++++++++++++++++++++++++++++++++++++++++++++
drivers/xen/pvcalls-front.h | 3 ++
2 files changed, 82 insertions(+)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 80fd5fb..f3a04a2 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -410,6 +410,85 @@ int pvcalls_front_listen(struct socket *sock, int backlog)
return ret;
}
+int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
+{
+ struct pvcalls_bedata *bedata;
+ struct sock_mapping *map;
+ struct sock_mapping *map2 = NULL;
+ struct xen_pvcalls_request *req;
+ int notify, req_id, ret, evtchn;
+
+ if (!pvcalls_front_dev)
+ return -ENOTCONN;
+ bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
+
+ map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head);
+ if (!map)
+ return -ENOTSOCK;
+
+ if (map->passive.status != PVCALLS_STATUS_LISTEN)
+ return -EINVAL;
+
+ /*
+ * Backend only supports 1 inflight accept request, will return
+ * errors for the others
+ */
+ if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
+ (void *)&map->passive.flags)) {
+ if (wait_event_interruptible(map->passive.inflight_accept_req,
+ !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
+ (void *)&map->passive.flags))
+ != 0)
+ return -EINTR;
+ }
+
+
+ newsock->sk = kzalloc(sizeof(*newsock->sk), GFP_KERNEL);
+ if (newsock->sk == NULL)
+ return -ENOMEM;
+
+ spin_lock(&bedata->pvcallss_lock);
+ req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
+ BUG_ON(req_id >= PVCALLS_NR_REQ_PER_RING);
+ if (RING_FULL(&bedata->ring) ||
+ READ_ONCE(bedata->rsp[req_id].req_id) != PVCALLS_INVALID_ID) {
+ spin_unlock(&bedata->pvcallss_lock);
+ return -EAGAIN;
+ }
+
+ map2 = create_active(&evtchn);
+
+ req = RING_GET_REQUEST(&bedata->ring, req_id);
+ req->req_id = req_id;
+ req->cmd = PVCALLS_ACCEPT;
+ req->u.accept.id = (uint64_t) sock;
+ req->u.accept.ref = map2->active.ref;
+ req->u.accept.id_new = (uint64_t) newsock;
+ req->u.accept.evtchn = evtchn;
+
+ list_add_tail(&map2->list, &bedata->socket_mappings);
+ WRITE_ONCE(newsock->sk->sk_send_head, (void *)map2);
+ map2->sock = newsock;
+
+ bedata->ring.req_prod_pvt++;
+ RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
+ spin_unlock(&bedata->pvcallss_lock);
+ if (notify)
+ notify_remote_via_irq(bedata->irq);
+
+ wait_event(bedata->inflight_req,
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+
+ clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
+ wake_up(&map->passive.inflight_accept_req);
+
+ ret = bedata->rsp[req_id].ret;
+ /* read ret, then set this rsp slot to be reused */
+ smp_mb();
+ WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
+ return ret;
+}
+
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 aa8fe10..ab4f1da 100644
--- a/drivers/xen/pvcalls-front.h
+++ b/drivers/xen/pvcalls-front.h
@@ -10,5 +10,8 @@ int pvcalls_front_bind(struct socket *sock,
struct sockaddr *addr,
int addr_len);
int pvcalls_front_listen(struct socket *sock, int backlog);
+int pvcalls_front_accept(struct socket *sock,
+ struct socket *newsock,
+ int flags);
#endif
--
1.9.1
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