Re: [PATCH bpf-next v2 02/16] xsk: Add getsockopt XDP_OPTIONS

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Maxim Mikityanskiy <maximmi@mellanox.com>
Cc: "Björn Töpel" <bjorn.topel@gmail.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Saeed Mahameed" <saeedm@mellanox.com>,
	"Jonathan Lemon" <bsd@fb.com>,
	"Tariq Toukan" <tariqt@mellanox.com>,
	"Martin KaFai Lau" <kafai@fb.com>,
	"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
	"Jakub Kicinski" <jakub.kicinski@netronome.com>,
	"Maciej Fijalkowski" <maciejromanfijalkowski@gmail.com>
Subject: Re: [PATCH bpf-next v2 02/16] xsk: Add getsockopt XDP_OPTIONS
Date: Mon, 6 May 2019 09:35:33 -0700	[thread overview]
Message-ID: <20190506163532.4zythaxnndpcueqh@ast-mbp> (raw)
In-Reply-To: <f00130ea-86a8-355c-76fb-bd0bea389e62@mellanox.com>

On Mon, May 06, 2019 at 01:45:40PM +0000, Maxim Mikityanskiy wrote:
> On 2019-05-04 20:25, Björn Töpel wrote:
> > On Tue, 30 Apr 2019 at 20:12, Maxim Mikityanskiy <maximmi@mellanox.com> wrote:
> >>
> >> Make it possible for the application to determine whether the AF_XDP
> >> socket is running in zero-copy mode. To achieve this, add a new
> >> getsockopt option XDP_OPTIONS that returns flags. The only flag
> >> supported for now is the zero-copy mode indicator.
> >>
> >> Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
> >> Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
> >> Acked-by: Saeed Mahameed <saeedm@mellanox.com>
> >> ---
> >>   include/uapi/linux/if_xdp.h       |  7 +++++++
> >>   net/xdp/xsk.c                     | 22 ++++++++++++++++++++++
> >>   tools/include/uapi/linux/if_xdp.h |  7 +++++++
> >>   3 files changed, 36 insertions(+)
> >>
> >> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> >> index caed8b1614ff..9ae4b4e08b68 100644
> >> --- a/include/uapi/linux/if_xdp.h
> >> +++ b/include/uapi/linux/if_xdp.h
> >> @@ -46,6 +46,7 @@ struct xdp_mmap_offsets {
> >>   #define XDP_UMEM_FILL_RING             5
> >>   #define XDP_UMEM_COMPLETION_RING       6
> >>   #define XDP_STATISTICS                 7
> >> +#define XDP_OPTIONS                    8
> >>
> >>   struct xdp_umem_reg {
> >>          __u64 addr; /* Start of packet data area */
> >> @@ -60,6 +61,12 @@ struct xdp_statistics {
> >>          __u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
> >>   };
> >>
> >> +struct xdp_options {
> >> +       __u32 flags;
> >> +};
> >> +
> >> +#define XDP_OPTIONS_FLAG_ZEROCOPY (1 << 0)
> > 
> > Nit: The other flags doesn't use "FLAG" in its name, but that doesn't
> > really matter.
> > 
> >> +
> >>   /* Pgoff for mmaping the rings */
> >>   #define XDP_PGOFF_RX_RING                        0
> >>   #define XDP_PGOFF_TX_RING               0x80000000
> >> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> >> index b68a380f50b3..998199109d5c 100644
> >> --- a/net/xdp/xsk.c
> >> +++ b/net/xdp/xsk.c
> >> @@ -650,6 +650,28 @@ static int xsk_getsockopt(struct socket *sock, int level, int optname,
> >>
> >>                  return 0;
> >>          }
> >> +       case XDP_OPTIONS:
> >> +       {
> >> +               struct xdp_options opts;
> >> +
> >> +               if (len < sizeof(opts))
> >> +                       return -EINVAL;
> >> +
> >> +               opts.flags = 0;
> > 
> > Maybe get rid of this, in favor of "opts = {}" if the structure grows?
> 
> I'm OK with any of these options. Should I respin the series, or can I 
> follow up with the change in RCs if the series gets to 5.2?
> 
> Alexei, is it even possible to still make changes to this series? The 
> window appears closed.

The series were not applied.
Please resubmit addressing all feedback when bpf-next reopens.
Likely in ~2 weeks.