linux-kernel - Re: [PATCH net-next v18 07/14] memory-provider: dmabuf devmem memory provider

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Message-ID: <20240809205236.77c959b0@kernel.org>
Date: Fri, 9 Aug 2024 20:52:36 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Pavel Begunkov <asml.silence@...il.com>
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Subject: Re: [PATCH net-next v18 07/14] memory-provider: dmabuf devmem
 memory provider

On Fri, 9 Aug 2024 16:45:50 +0100 Pavel Begunkov wrote:
> > I think this is good, and it doesn't seem hacky to me, because we can
> > check the page_pools of the netdev while we hold rtnl, so we can be
> > sure nothing is messing with the pp configuration in the meantime.
> > Like you say below it does validate the driver rather than rely on the
> > driver saying it's doing the right thing. I'll look into putting this
> > in the next version.  
> 
> Why not have a flag set by the driver and advertising whether it
> supports providers or not, which should be checked for instance in
> netdev_rx_queue_restart()? If set, the driver should do the right
> thing. That's in addition to a new pp_params flag explicitly telling
> if pp should use providers. It's more explicit and feels a little
> less hacky.

You mean like I suggested in the previous two emails? :)

Given how easy the check is to implement, I think it's worth
adding as a sanity check. But the flag should be the main API,
if the sanity check starts to be annoying we'll ditch it.