Re: [dpdk-dev] [PATCH v2] net/virtio: avoid annoying IOPL call related errors

[David Marchand <david.marchand@redhat.com>]

On Fri, Nov 23, 2018 at 3:36 PM Ilya Maximets <i.maximets@samsung.com>
wrote:

> In case of running with not enough capabilities, i.e. running as
> non-root user any application linked with DPDK prints the message
> about IOPL call failure even if it was just called like
> './testpmd --help'. For example, this beaks most of the OVS unit
> tests if it built with DPDK support.
>

breaks


>
> Let's register the virtio driver unconditionally and print error
> message while probing the device. Silent iopl() call left in the
> constructor to have privileges as early as possible as it was before.
>

Yes, that's the important part to avoid issues with the interrupt thread
which is spawned later and inherits the capa from the thread running
rte_eal_init, iirc.


> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
>

Reviewed-by: David Marchand <david.marchand@redhat.com>

I wonder if we could move the "new" iopl check even later when probing a
device since it only makes sense in legacy mode when using uio.
But this patch keeps previous behaviour.

diff --git a/lib/librte_eal/bsdapp/eal/eal.c
> b/lib/librte_eal/bsdapp/eal/eal.c
> index 508cbc46f..b8152a75c 100644
> --- a/lib/librte_eal/bsdapp/eal/eal.c
> +++ b/lib/librte_eal/bsdapp/eal/eal.c
> @@ -556,9 +556,11 @@ int rte_eal_has_hugepages(void)
>  int
>  rte_eal_iopl_init(void)
>  {
> -       static int fd;
> +       static int fd = -1;
> +
> +       if (fd < 0)
> +               fd = open("/dev/io", O_RDWR);
>
> -       fd = open("/dev/io", O_RDWR);
>         if (fd < 0)
>                 return -1;
>         /* keep fd open for iopl */
>

Good catch.
Should be a separate fix.


-- 
David Marchand