RE: [PATCH net] net: fec: tx processing does not call XDP APIs if budget is 0

On Thu, 27 Jul 2023 02:08:32 +0000 Wei Fang wrote:

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Actually after talking with Jakub a bit more there is an issue here,
but not freeing the frames isn't the solution. We likely need to
just fix the page pool code so that it doesn't attempt to recycle
the frames if operating in IRQ context.

The way this is dealt with for skbs is that we queue skbs if we are
in IRQ context so that it can be deferred to be freed by the
net_tx_action. We likely need to look at doing something similar for
page_pool pages or XDP frames.

After reading your discussion with Jakub, I understand this issue a bit more.
But we are not sure when this issue will be fixed in page pool,
currently we can only tolerate a delay in sending of a netpoll
message. So I think this patch is necessary, and I will refine it in
the future when the page pool has fixed the issue. In addition, as you
mentioned before, napi_consume_skb should be used to instead of

dev_kfree_skb_any, so I will improve this patch in version 2.

I think so too, since the patch can only help, you already wrote it and it won't
be extra backporting work since the code is only present in
6.5 - I think it's worth applying. And we can refine things as page pool
limitations get listed (the napi_consume_skb() is net-next material, anyway).

Okay, thank you. :)