xdp: bpf_xdp_metadata use EOPNOTSUPP for no driver support

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 ambiguous 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.

Fixes: ab46182d0dcb ("net/mlx4_en: Support RX XDP metadata")
Fixes: bc8d405b1ba9 ("net/mlx5e: Support RX XDP metadata")
Fixes: 306531f0249f ("veth: Support RX XDP metadata")
Fixes: 3d76a4d3d4e5 ("bpf: XDP metadata RX kfuncs")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/167940675120.2718408.8176058626864184420.stgit@firesoul
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
index aac63fc2d08bd104634315d422d33f24717de4aa..25ce72af81c216322edfe56da3195fdd13a47db8 100644 (file)
--- 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 0869d4fff17b1aa49dff0d4a6b21a8868afbd30d..4b5e459b6d49fee01508e0fff1e203ba3d1cee74 100644 (file)
--- 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 bcd6370de440f2d3c9f22509750c51c3899c382b..c5dae48b7932f7a6216f55cb3b14faa7d167e1c8 100644 (file)
--- 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 1bb54de7124d95e4974c158017ac6611a370c4d8..046461ee42ead0437737707bbaf2681a7c01fb6f 100644 (file)
--- 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 8c92fc55331771495b7c11fe5b4e660d8c11a11c..247797168579c37b50dad78d4b8bec83d74c4251 100644 (file)
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -720,7 +720,10 @@ __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)
 {
@@ -732,7 +735,10 @@ __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)
 {