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From: Jesper Dangaard Brouer <jbrouer@redhat.com>
To: Stanislav Fomichev <sdf@google.com>,
	Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc: brouer@redhat.com, bpf@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@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, intel-wired-lan@lists.osuosl.org,
	pabeni@redhat.com, jesse.brandeburg@intel.com, kuba@kernel.org,
	edumazet@google.com, john.fastabend@gmail.com, hawk@kernel.org,
	davem@davemloft.net
Subject: Re: [PATCH bpf RFC-V3 1/5] xdp: rss hash types representation
Date: Fri, 31 Mar 2023 13:49:15 +0200	[thread overview]
Message-ID: <39b58460-6322-2c07-990a-864dc210ba0a@redhat.com> (raw)
In-Reply-To: <c305e8ed-bd2c-3301-3a19-c983ff14a3ed@redhat.com>


On 30/03/2023 21.08, Jesper Dangaard Brouer wrote:
> 
> On 30/03/2023 21.02, Stanislav Fomichev wrote:
>> On Thu, Mar 30, 2023 at 11:56 AM Jesper Dangaard Brouer
>>>
>>> On 30/03/2023 20.35, Stanislav Fomichev wrote:
>>>> On 03/30, Jesper Dangaard Brouer wrote:
> [...]
>>> [...]
>>>>> diff --git a/net/core/xdp.c b/net/core/xdp.c
>>>>> index 528d4b37983d..38d2dee16b47 100644
>>>>> --- a/net/core/xdp.c
>>>>> +++ b/net/core/xdp.c
>>>>> @@ -734,14 +734,22 @@ __bpf_kfunc int
>>>>> bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx, u64 *tim
>>>>>     * bpf_xdp_metadata_rx_hash - Read XDP frame RX hash.
>>>>>     * @ctx: XDP context pointer.
>>>>>     * @hash: Return value pointer.
>>>>> + * @rss_type: Return value pointer for RSS type.
>>>>> + *
>>>>> + * The RSS hash type (@rss_type) specifies what portion of packet 
>>>>> headers NIC
>>>>> + * hardware were used when calculating RSS hash value.  The type 
>>>>> combinations
>>>>> + * are defined via &enum xdp_rss_hash_type and individual bits can 
>>>>> be decoded
>>>>> + * via &enum xdp_rss_type_bits.
>>>>>     *
>>>>>     * 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)
>>>>> +__bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
>>>>> u32 *hash,
>>>>> +                     enum xdp_rss_hash_type *rss_type)
>>>>>    {
>>>> [..]
>>>>
>>>>> +    BTF_TYPE_EMIT(enum xdp_rss_type_bits);
>>>> nit: Do we still need this with an extra argument?
>>>>
>>> Yes, unfortunately (compiler optimizes out enum xdp_rss_type_bits).
>>> Do notice the difference xdp_rss_type_bits vs xdp_rss_hash_type.
>>> We don't need it for "xdp_rss_hash_type" but need it for
>>> "xdp_rss_type_bits".
>  >
>> Ah, I missed that. Then why not expose xdp_rss_type_bits?
>> Keep xdp_rss_hash_type for internal drivers' tables, and export the
>> enum with the bits?
> 
> Great suggestion, xdp_rss_hash_type will be internal for drivers.
> I will do that in V4.

I'm running into annoying compiler warnings [-Wenum-conversion]
about enum conversions.  I'll try to workaround this...
The easiest solution seem to be to only have a single enum, that both 
contains the BIT()s and combinations of bits (for driver usage).

E.g.
  warning: implicit conversion from 'enum xdp_rss_type_bits' to 'enum 
xdp_rss_hash_type' [-Wenum-conversion]


  reply	other threads:[~2023-03-31 11:50 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-30 17:07 [PATCH bpf RFC-V3 0/5] XDP-hints: API change for RX-hash kfunc bpf_xdp_metadata_rx_hash Jesper Dangaard Brouer
2023-03-30 17:07 ` [PATCH bpf RFC-V3 1/5] xdp: rss hash types representation Jesper Dangaard Brouer
2023-03-30 18:35   ` Stanislav Fomichev
2023-03-30 18:56     ` Jesper Dangaard Brouer
2023-03-30 19:02       ` Stanislav Fomichev
2023-03-30 19:08         ` Jesper Dangaard Brouer
2023-03-31 11:49           ` Jesper Dangaard Brouer [this message]
2023-03-30 17:07 ` [PATCH bpf RFC-V3 2/5] mlx5: bpf_xdp_metadata_rx_hash add xdp rss hash type Jesper Dangaard Brouer
2023-03-30 17:07 ` [PATCH bpf RFC-V3 3/5] veth: " Jesper Dangaard Brouer
2023-03-30 17:08 ` [PATCH bpf RFC-V3 4/5] mlx4: " Jesper Dangaard Brouer
2023-03-30 17:08 ` [PATCH bpf RFC-V3 5/5] selftests/bpf: Adjust bpf_xdp_metadata_rx_hash for new arg Jesper Dangaard Brouer
2023-03-30 18:38 ` [PATCH bpf RFC-V3 0/5] XDP-hints: API change for RX-hash kfunc bpf_xdp_metadata_rx_hash Stanislav Fomichev
2023-03-30 19:04   ` Jesper Dangaard Brouer
2023-03-30 19:24 ` [xdp-hints] " Toke Høiland-Jørgensen

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