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    SubjectRe: [PATCH v1 05/13] xen/pvcalls: implement bind command
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    On 22/07/17 02:11, Stefano Stabellini wrote:
    > Send PVCALLS_BIND to the backend. Introduce a new structure, part of
    > struct sock_mapping, to store information specific to passive sockets.
    >
    > Introduce a status field to keep track of the status of the passive
    > socket.
    >
    > Introduce a waitqueue for the "accept" command (see the accept command
    > implementation): it is used to allow only one outstanding accept
    > command at any given time and to implement polling on the passive
    > socket. Introduce a flags field to keep track of in-flight accept and
    > poll commands.
    >
    > 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 struct socket pointer into an uint64_t and use it as id for
    > the socket to pass to the backend.
    >
    > Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
    > CC: boris.ostrovsky@oracle.com
    > CC: jgross@suse.com
    > ---
    > drivers/xen/pvcalls-front.c | 74 +++++++++++++++++++++++++++++++++++++++++++++
    > drivers/xen/pvcalls-front.h | 3 ++
    > 2 files changed, 77 insertions(+)
    >
    > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
    > index 0d305e0..71619bc 100644
    > --- a/drivers/xen/pvcalls-front.c
    > +++ b/drivers/xen/pvcalls-front.c
    > @@ -57,6 +57,23 @@ struct sock_mapping {
    >
    > wait_queue_head_t inflight_conn_req;
    > } active;
    > + struct {
    > + /* Socket status */
    > +#define PVCALLS_STATUS_UNINITALIZED 0
    > +#define PVCALLS_STATUS_BIND 1
    > +#define PVCALLS_STATUS_LISTEN 2
    > + uint8_t status;
    > + /*
    > + * Internal state-machine flags.
    > + * Only one accept operation can be inflight for a socket.
    > + * Only one poll operation can be inflight for a given socket.
    > + */
    > +#define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
    > +#define PVCALLS_FLAG_POLL_INFLIGHT 1
    > +#define PVCALLS_FLAG_POLL_RET 2
    > + uint8_t flags;
    > + wait_queue_head_t inflight_accept_req;
    > + } passive;
    > };
    > };
    >
    > @@ -287,6 +304,63 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
    > return ret;
    > }
    >
    > +int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
    > +{
    > + struct pvcalls_bedata *bedata;
    > + struct sock_mapping *map = NULL;
    > + struct xen_pvcalls_request *req;
    > + int notify, req_id, ret;
    > +
    > + if (!pvcalls_front_dev)
    > + return -ENOTCONN;
    > + if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
    > + return -ENOTSUPP;
    > + bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
    > +
    > + map = kzalloc(sizeof(*map), GFP_KERNEL);
    > + if (map == 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);

    BUG_ON() isn't appropriate here. The system can still be used.


    Juergen

    > + if (RING_FULL(&bedata->ring) ||
    > + READ_ONCE(bedata->rsp[req_id].req_id) != PVCALLS_INVALID_ID) {
    > + kfree(map);
    > + spin_unlock(&bedata->pvcallss_lock);
    > + return -EAGAIN;
    > + }
    > + req = RING_GET_REQUEST(&bedata->ring, req_id);
    > + req->req_id = req_id;
    > + map->sock = sock;
    > + req->cmd = PVCALLS_BIND;
    > + req->u.bind.id = (uint64_t) sock;
    > + memcpy(req->u.bind.addr, addr, sizeof(*addr));
    > + req->u.bind.len = addr_len;
    > +
    > + init_waitqueue_head(&map->passive.inflight_accept_req);
    > +
    > + list_add_tail(&map->list, &bedata->socketpass_mappings);
    > + WRITE_ONCE(sock->sk->sk_send_head, (void *)map);
    > + map->active_socket = false;
    > +
    > + 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);
    > +
    > + map->passive.status = PVCALLS_STATUS_BIND;
    > + 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 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 63b0417..8b0a274 100644
    > --- a/drivers/xen/pvcalls-front.h
    > +++ b/drivers/xen/pvcalls-front.h
    > @@ -6,5 +6,8 @@
    > int pvcalls_front_socket(struct socket *sock);
    > int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
    > int addr_len, int flags);
    > +int pvcalls_front_bind(struct socket *sock,
    > + struct sockaddr *addr,
    > + int addr_len);
    >
    > #endif
    >

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