RE: [EXT] Re: [PATCH v4 1/2] net: page_pool: export page_pool_stats definition

[Shenwei Wang]

> -----Original Message-----
> From: Andrew Lunn <andrew@xxxxxxx>
> Sent: Tuesday, November 15, 2022 11:12 AM
> To: Shenwei Wang <shenwei.wang@xxxxxxx>
> Cc: David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni
> <pabeni@xxxxxxxxxx>; Jesper Dangaard Brouer <hawk@xxxxxxxxxx>; Ilias
> Apalodimas <ilias.apalodimas@xxxxxxxxxx>; Alexei Starovoitov
> <ast@xxxxxxxxxx>; Daniel Borkmann <daniel@xxxxxxxxxxxxx>; John Fastabend
> <john.fastabend@xxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH v4 1/2] net: page_pool: export page_pool_stats
> definition
> 
> Caution: EXT Email
> 
> On Tue, Nov 15, 2022 at 09:57:43AM -0600, Shenwei Wang wrote:
> > The definition of the 'struct page_pool_stats' is required even when
> > the CONFIG_PAGE_POOL_STATS is not defined. Otherwise, it is required
> > the drivers to handle the case of CONFIG_PAGE_POOL_STATS undefined.
> 
> I agree the API is broken, but i think there is a better fix.
> 
> There should be a stub of page_pool_get_stats() for when
> CONFIG_PAGE_POOL_STATS is disabled.
> 
> Nothing actually dereferences struct page_pool_stats when you have this stub.
> So it might be enough to simply have
> 
> struct page_pool_stats{
> };
> 

As the structure is open when the CONFIG_PAGE_POOL_STATS is enabled, you can not
prevent a user to access its members. The empty stub will still have problems in this
kind of situations.

Regards,
Shenwei

>        Andrew