From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31EBCC6FD1D for ; Fri, 17 Mar 2023 21:22:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229844AbjCQVV7 (ORCPT ); Fri, 17 Mar 2023 17:21:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229733AbjCQVV6 (ORCPT ); Fri, 17 Mar 2023 17:21:58 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58B71C795B for ; Fri, 17 Mar 2023 14:21:51 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id i6-20020a170902c94600b0019d16e4ac0bso3298430pla.5 for ; Fri, 17 Mar 2023 14:21:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679088110; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=PzsBZNbSc5Cbu7o6c4aa6/HqL8bVQjVwQw8nR/BqY10=; b=M3pyj4WXzRt5UOa9AGraYYh1SMXzBIrCA12O1wU1pGc3u4z8qivxajOailzHPT20mJ bB42c+Ws9X1LLYsiqQD6IZe1BJSIllAIVbN2utQOdT9d1jyqlBDpt99ebpcOKI5zDZpt rUqxrV6frBBIY7ISv1P4cvRqIrH3xvBCAiQVFgLxcC9muYMA8LOuBs3AlEIU9lIYtD8y kXg8mlfbVKAibTjQ5fdhWcU0ocFMf4zVJhI4nde1oGlTuxESqEml0JFrPQjL5fDA/2s8 1+ghb9aXrSg8QzQjteR7mPTcQWf4tIH184yf43wOd077i9g8I+P8btQ11XZFGpKU8aIe EQBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679088110; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=PzsBZNbSc5Cbu7o6c4aa6/HqL8bVQjVwQw8nR/BqY10=; b=smVaJcPYpPszNXVo1MaGkPVz5H5bz8yxb/4FyXJjwsbx1PQuzuABYLaEm+U4GKiqaq KSYszAdTChHwYCKbAKXYO7rLg3fKbxhjsSNaoa/C4lGxbMRZieSQMXGeJPBQp4l9czO8 t6+AAM8s2+osk2lZxud46I6sEay9QU1YtJA5sawmB8StNWPgdvye0x1kNJORm5R/dL6C RENoy5igh34BSFhn1+6teu4XX2wnvkx+53Tps+5zdAgcwkJmXKb47CqTJI18YJqhuxI+ xbgXdJOwHOx1mOVUJCzPznBEK9oR5Y97Show6mjfqj6jzMOYIWvgGauESTqg5qtla6N6 RRbg== X-Gm-Message-State: AO0yUKWFuR74l8acZhTqPkuTDJTeW6P8JTZAHfzgmu/2mPyk3dyw94T/ tjucAyDcw+NanU9SuQEPPyimQog= X-Google-Smtp-Source: AK7set9tu9oc1RUjxgzKPCg+fE9JjxddXFmRXUmD2tbjQ8Qh5j337E8HODQsf2FImw0oHf/u/g7DsGE= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a17:903:2585:b0:19f:28f4:1db with SMTP id jb5-20020a170903258500b0019f28f401dbmr3468766plb.8.1679088110486; Fri, 17 Mar 2023 14:21:50 -0700 (PDT) Date: Fri, 17 Mar 2023 14:21:48 -0700 In-Reply-To: <167906359575.2706833.545256364239637451.stgit@firesoul> Mime-Version: 1.0 References: <167906343576.2706833.17489167761084071890.stgit@firesoul> <167906359575.2706833.545256364239637451.stgit@firesoul> Message-ID: Subject: Re: [PATCH bpf-next V1 1/7] xdp: bpf_xdp_metadata use EOPNOTSUPP for no driver support From: Stanislav Fomichev To: Jesper Dangaard Brouer Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, martin.lau@kernel.org, ast@kernel.org, daniel@iogearbox.net, alexandr.lobakin@intel.com, larysa.zaremba@intel.com, xdp-hints@xdp-project.net, anthony.l.nguyen@intel.com, yoong.siang.song@intel.com, boon.leong.ong@intel.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 03/17, Jesper Dangaard Brouer wrote: > When driver doesn't implement a bpf_xdp_metadata kfunc the fallback > implementation returns EOPNOTSUPP, which indicate device driver doesn't > implement this kfunc. > Currently many drivers also return EOPNOTSUPP when the hint isn't > available, which is inconsistent from an API point of view. Instead > change drivers to return ENODATA in these cases. > There can be natural cases why a driver doesn't provide any hardware > info for a specific hint, even on a frame to frame basis (e.g. PTP). > Lets keep these cases as separate return codes. > When describing the return values, adjust the function kernel-doc layout > to get proper rendering for the return values. > Signed-off-by: Jesper Dangaard Brouer I don't remember whether the previous discussion ended in something? IIRC Martin was preferring to use xdp-features for this instead? Personally I'm fine with having this convention, but I'm not sure how well we'll be able to enforce them. (In general, I'm not a fan of userspace changing it's behavior based on errno. If it's mostly for debugging/development - seems ok) > --- > Documentation/networking/xdp-rx-metadata.rst | 7 +++++-- > drivers/net/ethernet/mellanox/mlx4/en_rx.c | 4 ++-- > drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 4 ++-- > drivers/net/veth.c | 4 ++-- > net/core/xdp.c | 10 ++++++++-- > 5 files changed, 19 insertions(+), 10 deletions(-) > diff --git a/Documentation/networking/xdp-rx-metadata.rst > b/Documentation/networking/xdp-rx-metadata.rst > index aac63fc2d08b..25ce72af81c2 100644 > --- a/Documentation/networking/xdp-rx-metadata.rst > +++ b/Documentation/networking/xdp-rx-metadata.rst > @@ -23,10 +23,13 @@ metadata is supported, this set will grow: > An XDP program can use these kfuncs to read the metadata into stack > variables for its own consumption. Or, to pass the metadata on to other > consumers, an XDP program can store it into the metadata area carried > -ahead of the packet. > +ahead of the packet. Not all packets will necessary have the requested > +metadata available in which case the driver returns ``-ENODATA``. > Not all kfuncs have to be implemented by the device driver; when not > -implemented, the default ones that return ``-EOPNOTSUPP`` will be used. > +implemented, the default ones that return ``-EOPNOTSUPP`` will be used > +to indicate the device driver have not implemented this kfunc. > + > Within an XDP frame, the metadata layout (accessed via ``xdp_buff``) is > as follows:: > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > index 0869d4fff17b..4b5e459b6d49 100644 > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > @@ -674,7 +674,7 @@ int mlx4_en_xdp_rx_timestamp(const struct xdp_md > *ctx, u64 *timestamp) > struct mlx4_en_xdp_buff *_ctx = (void *)ctx; > if (unlikely(_ctx->ring->hwtstamp_rx_filter != HWTSTAMP_FILTER_ALL)) > - return -EOPNOTSUPP; > + return -ENODATA; > *timestamp = mlx4_en_get_hwtstamp(_ctx->mdev, > mlx4_en_get_cqe_ts(_ctx->cqe)); > @@ -686,7 +686,7 @@ int mlx4_en_xdp_rx_hash(const struct xdp_md *ctx, u32 > *hash) > struct mlx4_en_xdp_buff *_ctx = (void *)ctx; > if (unlikely(!(_ctx->dev->features & NETIF_F_RXHASH))) > - return -EOPNOTSUPP; > + return -ENODATA; > *hash = be32_to_cpu(_ctx->cqe->immed_rss_invalid); > return 0; > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c > b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c > index bcd6370de440..c5dae48b7932 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c > @@ -162,7 +162,7 @@ static int mlx5e_xdp_rx_timestamp(const struct xdp_md > *ctx, u64 *timestamp) > const struct mlx5e_xdp_buff *_ctx = (void *)ctx; > if (unlikely(!mlx5e_rx_hw_stamp(_ctx->rq->tstamp))) > - return -EOPNOTSUPP; > + return -ENODATA; > *timestamp = mlx5e_cqe_ts_to_ns(_ctx->rq->ptp_cyc2time, > _ctx->rq->clock, get_cqe_ts(_ctx->cqe)); > @@ -174,7 +174,7 @@ static int mlx5e_xdp_rx_hash(const struct xdp_md > *ctx, u32 *hash) > const struct mlx5e_xdp_buff *_ctx = (void *)ctx; > if (unlikely(!(_ctx->xdp.rxq->dev->features & NETIF_F_RXHASH))) > - return -EOPNOTSUPP; > + return -ENODATA; > *hash = be32_to_cpu(_ctx->cqe->rss_hash_result); > return 0; > diff --git a/drivers/net/veth.c b/drivers/net/veth.c > index 1bb54de7124d..046461ee42ea 100644 > --- a/drivers/net/veth.c > +++ b/drivers/net/veth.c > @@ -1610,7 +1610,7 @@ static int veth_xdp_rx_timestamp(const struct > xdp_md *ctx, u64 *timestamp) > struct veth_xdp_buff *_ctx = (void *)ctx; > if (!_ctx->skb) > - return -EOPNOTSUPP; > + return -ENODATA; > *timestamp = skb_hwtstamps(_ctx->skb)->hwtstamp; > return 0; > @@ -1621,7 +1621,7 @@ static int veth_xdp_rx_hash(const struct xdp_md > *ctx, u32 *hash) > struct veth_xdp_buff *_ctx = (void *)ctx; > if (!_ctx->skb) > - return -EOPNOTSUPP; > + return -ENODATA; > *hash = skb_get_hash(_ctx->skb); > return 0; > diff --git a/net/core/xdp.c b/net/core/xdp.c > index 8d3ad315f18d..7133017bcd74 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -705,7 +705,10 @@ __diag_ignore_all("-Wmissing-prototypes", > * @ctx: XDP context pointer. > * @timestamp: Return value pointer. > * > - * Returns 0 on success or ``-errno`` on error. > + * Return: > + * * Returns 0 on success or ``-errno`` on error. > + * * ``-EOPNOTSUPP`` : means device driver does not implement kfunc > + * * ``-ENODATA`` : means no RX-timestamp available for this frame > */ > __bpf_kfunc int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx, > u64 *timestamp) > { > @@ -717,7 +720,10 @@ __bpf_kfunc int bpf_xdp_metadata_rx_timestamp(const > struct xdp_md *ctx, u64 *tim > * @ctx: XDP context pointer. > * @hash: Return value pointer. > * > - * Returns 0 on success or ``-errno`` on error. > + * Return: > + * * Returns 0 on success or ``-errno`` on error. > + * * ``-EOPNOTSUPP`` : means device driver doesn't implement kfunc > + * * ``-ENODATA`` : means no RX-hash available for this frame > */ > __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 > *hash) > {