[openib-general] Re: [PATCH/RFC] change ibv_get_devices() to ibv_get_device_list()

[Michael S. Tsirkin]

Quoting Roland Dreier <rdreier at cisco.com>:
> --- userspace/mpi/mvapich-gen2/mpid/ch_gen2/viainit.c	(revision 4360)
> +++ userspace/mpi/mvapich-gen2/mpid/ch_gen2/viainit.c	(working copy)
> @@ -74,13 +74,22 @@ static void set_malloc_options(void)
>  
>  static void open_hca(void)
>  {
> -    struct dlist *dev_list;
>      struct ibv_device *ib_dev = NULL;
>  
> +#ifdef GEN2_OLD_DEVICE_LIST_VERB
> +    struct dlist *dev_list;
> +
>      dev_list = ibv_get_devices();
>  
>      dlist_start(dev_list);
>      ib_dev = dlist_next(dev_list);
> +#else
> +    struct ibv_device **dev_list;
> +
> +    dev_list = ibv_get_device_list(NULL);
> +    ib_dev = dev_list[0];
> +    ibv_free_device_list(dev_list);
> +#endif
>  
>      if (!ib_dev) {
>          fprintf(stderr, "No IB devices found\n");

This wont work for hotplug: you are saving the device pointer
without opening the device, so it might go away from under your feet.

I wander whether we can come up with an API that helps people
get it right more easily?

-- 
MST