netdev - Re: [RFC v3 01/18] netmem: introduce struct netmem

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Message-ID: <3df479c7-e42f-41e1-bc5e-88f3d783c5d1@samba.org>
Date: Tue, 3 Jun 2025 11:22:33 +0200
From: Stefan Metzmacher <metze@...ba.org>
To: Mina Almasry <almasrymina@...gle.com>, Byungchul Park <byungchul@...com>
Cc: willy@...radead.org, netdev@...r.kernel.org,
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Subject: Re: [RFC v3 01/18] netmem: introduce struct netmem_desc mirroring
 struct page

Hi Mina,

>> Do you mean?
>>
>>    struct net_iov {
>>      /* Union for anonymous aliasing: */
>>      union {
>>        struct netmem_desc desc;
>>        struct {
>>           unsigned long _flags;
>>           unsigned long pp_magic;
>>           struct page_pool *pp;
>>           unsigned long _pp_mapping_pad;
>>           unsigned long dma_addr;
>>           atomic_long_t pp_ref_count;
>>        };
>>      };
>>      struct net_iov_area *owner;
>>      enum net_iov_type type;
>>    };
>>
>> Right?  If so, I will.
>>
> 
> Yes, sounds good.
> 
> Also, maybe having a union with the same fields for anonymous aliasing
> can be error prone if someone updates netmem_desc and forgets to
> update the mirror in struct net_iov. If you can think of a way to deal
> with that, great, if not lets maybe put a comment on top of struct
> netmem_desc:

I haven't looked at the patch in detail, but to me it sounds
a bit like the checks io_uring_init is doing.

I hope this is in same way helpful here :-)

metze