linux-kernel - Re: [PATCH net-next v3 3/5] page_pool: Allow drivers to hint on SKB recycling

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Message-ID: <CAFnufp0aRJnJU4ZvLnp+zj2mp7FkgXGTon5JDFDU4BMoPsdUaQ@mail.gmail.com>
Date:   Sat, 10 Apr 2021 02:39:27 +0200
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc:     netdev@...r.kernel.org, linux-mm@...ck.org,
        Ayush Sawal <ayush.sawal@...lsio.com>,
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Subject: Re: [PATCH net-next v3 3/5] page_pool: Allow drivers to hint on SKB recycling

On Sat, Apr 10, 2021 at 2:11 AM Ilias Apalodimas
<ilias.apalodimas@...aro.org> wrote:
>
> Hi Matteo,
>
> [...]
> > +bool page_pool_return_skb_page(void *data);
> > +
> >  struct page_pool *page_pool_create(const struct page_pool_params *params);
> >
> >  #ifdef CONFIG_PAGE_POOL
> > @@ -243,4 +247,13 @@ static inline void page_pool_ring_unlock(struct page_pool *pool)
> >               spin_unlock_bh(&pool->ring.producer_lock);
> >  }
> >
> > +/* Store mem_info on struct page and use it while recycling skb frags */
> > +static inline
> > +void page_pool_store_mem_info(struct page *page, struct xdp_mem_info *mem)
> > +{
> > +     u32 *xmi = (u32 *)mem;
> > +
>
> I just noticed this changed from the original patchset I was carrying.
> On the original, I had a union containing a u32 member to explicitly avoid
> this casting. Let's wait for comments on the rest of the series, but i'd like
> to change that back in a v4. Aplogies, I completely missed this on the
> previous postings ...
>

Hi,

I had to change this because including net/xdp.h here caused a
circular dependency.
I think that the safest thing we can do is to use memcpy(), which will
handle the alignments correctly, depending on the architecture.

Cheers,
-- 
per aspera ad upstream