Re: [Xen-devel] [PATCH v4 11/18] xen/pvcalls: implement accept command

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

>  static void __pvcalls_back_accept(struct work_struct *work)
>  {
> +     struct sockpass_mapping *mappass = container_of(
> +             work, struct sockpass_mapping, register_work);
> +     struct sock_mapping *map;
> +     struct pvcalls_ioworker *iow;
> +     struct pvcalls_fedata *fedata;
> +     struct socket *sock;
> +     struct xen_pvcalls_response *rsp;
> +     struct xen_pvcalls_request *req;
> +     int notify;
> +     int ret = -EINVAL;
> +     unsigned long flags;
> +
> +     fedata = mappass->fedata;
> +     /*
> +      * __pvcalls_back_accept can race against pvcalls_back_accept.
> +      * We only need to check the value of "cmd" on read. It could be
> +      * done atomically, but to simplify the code on the write side, we
> +      * use a spinlock.
> +      */
> +     spin_lock_irqsave(&mappass->copy_lock, flags);
> +     req = &mappass->reqcopy;
> +     if (req->cmd != PVCALLS_ACCEPT) {
> +             spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +             return;
> +     }
> +     spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +
> +     sock = sock_alloc();
> +     if (sock == NULL)
> +             goto out_error;
> +     sock->type = mappass->sock->type;
> +     sock->ops = mappass->sock->ops;
> +
> +     ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
> +     if (ret == -EAGAIN) {
> +             sock_release(sock);
> +             goto out_error;
> +     }
> +
> +     map = pvcalls_new_active_socket(fedata,
> +                                     req->u.accept.id_new,
> +                                     req->u.accept.ref,
> +                                     req->u.accept.evtchn,
> +                                     sock);
> +     if (!map) {
> +             sock_release(sock);
> +             goto out_error;

Again, lost ret value.

> +     }
> +
> +     map->sockpass = mappass;
> +     iow = &map->ioworker;
> +     atomic_inc(&map->read);
> +     atomic_inc(&map->io);
> +     queue_work(iow->wq, &iow->register_work);
> +
> +out_error:
> +     rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +     rsp->req_id = req->req_id;
> +     rsp->cmd = req->cmd;
> +     rsp->u.accept.id = req->u.accept.id;
> +     rsp->ret = ret;
> +     RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
> +     if (notify)
> +             notify_remote_via_irq(fedata->irq);
> +
> +     mappass->reqcopy.cmd = 0;
>  }
>  
>  static void pvcalls_pass_sk_data_ready(struct sock *sock)
>  {
> +     struct sockpass_mapping *mappass = sock->sk_user_data;
> +
> +     if (mappass == NULL)
> +             return;
> +
> +     queue_work(mappass->wq, &mappass->register_work);
>  }
>  
>  static int pvcalls_back_bind(struct xenbus_device *dev,
> @@ -383,6 +456,43 @@ static int pvcalls_back_listen(struct xenbus_device *dev,
>  static int pvcalls_back_accept(struct xenbus_device *dev,
>                              struct xen_pvcalls_request *req)
>  {
> +     struct pvcalls_fedata *fedata;
> +     struct sockpass_mapping *mappass;
> +     int ret = -EINVAL;

Unnecessary initialization.

-boris

> +     struct xen_pvcalls_response *rsp;
> +     unsigned long flags;
> +
> +     fedata = dev_get_drvdata(&dev->dev);
> +
> +     mappass = radix_tree_lookup(&fedata->socketpass_mappings,
> +             req->u.accept.id);
> +     if (mappass == NULL)
> +             goto out_error;
> +
> +     /* 
> +      * Limitation of the current implementation: only support one
> +      * concurrent accept or poll call on one socket.
> +      */
> +     spin_lock_irqsave(&mappass->copy_lock, flags);
> +     if (mappass->reqcopy.cmd != 0) {
> +             spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +             ret = -EINTR;
> +             goto out_error;
> +     }
> +
> +     mappass->reqcopy = *req;
> +     spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +     queue_work(mappass->wq, &mappass->register_work);
> +
> +     /* Tell the caller we don't need to send back a notification yet */
> +     return -1;
> +
> +out_error:
> +     rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +     rsp->req_id = req->req_id;
> +     rsp->cmd = req->cmd;
> +     rsp->u.accept.id = req->u.accept.id;
> +     rsp->ret = ret;
>       return 0;
>  }
>  


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