Re: [RFC PATCH v3 08/12] net: support non paged skb frags

[Yunsheng Lin]

On 2023/11/8 5:19, Mina Almasry wrote:
>>
>>
> 
> My personal immediate reaction is that this may just introduce code
> churn without significant benefit. If an unsuspecting caller call
> skb_frag_page() on devmem frag and doesn't correctly handle NULL
> return, it will crash or error out anyway, and likely in some obvious
> way, so maybe the BUG_ON() isn't so useful that it's worth changing

If it will always crash or error out, then I agree that BUG_ON() is
unnecessary.

> all the call sites. But if there is consensus on adding a change like
> you propose, I have no problem adding it.

One obvious benefit I forget to mention is that, it provides a better
semantic that if a caller need to do the return checking:
1. For the old helper, the semantic is not to do the checking if the caller
   has ensure that it has passed a readable frag to skb_frag_page(), which
   avoid adding some overhead for non-devmen supported drivers.
2. For the new helper, the semantic is to do the checking and we may provide
   a compiler '__must_check' function-attribute to ensure the caller to do
   the checking.


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