Re: [Minios-devel] [UNIKRAFT PATCH v4 7/7] plat/xen: Add driver state functions to client API

[Yuri Volchkov <yuri.volchkov@xxxxxxxxx>]

Reviewed-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>

Costin Lupu <costin.lupu@xxxxxxxxx> writes:

> Extend the client API with functions for dealing with Xenbus driver
> states.
>
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> ---
>  plat/xen/include/xenbus/client.h | 24 ++++++++++
>  plat/xen/xenbus/client.c         | 95 
> ++++++++++++++++++++++++++++++++++++++++
>  plat/xen/xenbus/exportsyms.uk    |  2 +
>  3 files changed, 121 insertions(+)
>
> diff --git a/plat/xen/include/xenbus/client.h 
> b/plat/xen/include/xenbus/client.h
> index 8b7e8c1..a9417a9 100644
> --- a/plat/xen/include/xenbus/client.h
> +++ b/plat/xen/include/xenbus/client.h
> @@ -98,4 +98,28 @@ int xenbus_watch_notify_event(struct xenbus_watch *watch);
>   */
>  XenbusState xenbus_read_driver_state(const char *path);
>  
> +/*
> + * Changes the state of a Xen PV driver
> + *
> + * @param xbt Xenbus transaction id
> + * @param xendev Xenbus device
> + * @param state The new Xenbus state
> + * @return 0 on success, a negative errno value on error.
> + */
> +int xenbus_switch_state(xenbus_transaction_t xbt,
> +     struct xenbus_device *xendev, XenbusState state);
> +
> +/*
> + * Waits for the driver state found at the given Xenstore path to change by
> + * using watches.
> + *
> + * @param path Xenstore path
> + * @param state The returned Xenbus state
> + * @param watch Xenbus watch. It may be NULL, in which case a local watch
> + * will be created.
> + * @return 0 on success, a negative errno value on error.
> + */
> +int xenbus_wait_for_state_change(const char *path, XenbusState *state,
> +     struct xenbus_watch *watch);
> +
>  #endif /* __XENBUS_CLIENT_H__ */
> diff --git a/plat/xen/xenbus/client.c b/plat/xen/xenbus/client.c
> index 274e6e7..86725e3 100644
> --- a/plat/xen/xenbus/client.c
> +++ b/plat/xen/xenbus/client.c
> @@ -142,3 +142,98 @@ XenbusState xenbus_read_driver_state(const char *path)
>  
>       return state;
>  }
> +
> +int xenbus_switch_state(xenbus_transaction_t xbt,
> +     struct xenbus_device *xendev, XenbusState state)
> +{
> +     char state_path[strlen(xendev->nodename) + sizeof("/state")];
> +     char new_state_str[2];
> +     XenbusState crnt_state;
> +     int need_transaction_end = 0; /* non-zero if local transaction */
> +     int abort;
> +     int err;
> +
> +     if (xendev == NULL)
> +             return -EINVAL;
> +
> +     sprintf(state_path, "%s/state", xendev->nodename);
> +
> +     do {
> +             abort = 1;
> +
> +             if (xbt == XBT_NIL) {
> +                     err = xs_transaction_start(&xbt);
> +                     if (err)
> +                             goto exit;
> +                     need_transaction_end = 1;
> +             }
> +
> +             /* check if state is already set */
> +             err = xs_read_integer(xbt, xendev->nodename,
> +                     (int *) &crnt_state);
> +             if (err || crnt_state == state)
> +                     goto exit;
> +
> +             /* set new state */
> +             snprintf(new_state_str, sizeof(new_state_str), "%d", state);
> +             err = xs_write(xbt, state_path, NULL, new_state_str);
> +
> +             abort = 0;
> +exit:
> +             if (need_transaction_end) {
> +                     int _err;
> +
> +                     _err = xs_transaction_end(xbt, abort);
> +                     if (!err)
> +                             err = _err;
> +                     xbt = XBT_NIL;
> +             }
> +     } while (err == -EAGAIN);
> +
> +     if (err)
> +             uk_printd(DLVL_ERR, "Error switching state to %s: %d\n",
> +                     xenbus_state_to_str(state), err);
> +
> +     return err;
> +}
> +
> +int xenbus_wait_for_state_change(const char *path, XenbusState *state,
> +     struct xenbus_watch *watch)
> +{
> +     XenbusState crnt_state;
> +     int err = 0, watch_is_local = 0;
> +
> +     if (path == NULL || state == NULL) {
> +             err = -EINVAL;
> +             goto out;
> +     }
> +
> +     if (watch == NULL) {
> +             /* create a local watch */
> +             watch = xs_watch_path(XBT_NIL, path);
> +             if (PTRISERR(watch)) {
> +                     err = PTR2ERR(watch);
> +                     goto out;
> +             }
> +             watch_is_local = 1;
> +     }
> +
> +     for (;;) {
> +             err = xs_read_integer(XBT_NIL, path, (int *) &crnt_state);
> +             if (err)
> +                     break;
> +
> +             if (crnt_state != *state) {
> +                     *state = crnt_state;
> +                     break;
> +             }
> +
> +             xenbus_watch_wait_event(watch);
> +     }
> +
> +out:
> +     if (watch_is_local)
> +             xs_unwatch(XBT_NIL, watch);
> +
> +     return err;
> +}
> diff --git a/plat/xen/xenbus/exportsyms.uk b/plat/xen/xenbus/exportsyms.uk
> index d57a2a5..a750ff2 100644
> --- a/plat/xen/xenbus/exportsyms.uk
> +++ b/plat/xen/xenbus/exportsyms.uk
> @@ -28,3 +28,5 @@ xenbus_devtype_to_str
>  xenbus_str_to_devtype
>  xenbus_watch_wait_event
>  xenbus_read_driver_state
> +xenbus_switch_state
> +xenbus_wait_for_state_change
> -- 
> 2.11.0
>

-- 
Yuri Volchkov
Software Specialist

NEC Europe Ltd
Kurfürsten-Anlage 36
D-69115 Heidelberg

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