netdev - Re: [PATCH v1 14/15] io_uring/zcrx: set pp memory provider for an rx queue

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Message-ID: <53f1284c-6298-4b55-b7e8-9d480148ec5b@kernel.dk>
Date: Wed, 9 Oct 2024 12:42:20 -0600
From: Jens Axboe <axboe@...nel.dk>
To: David Wei <dw@...idwei.uk>, io-uring@...r.kernel.org,
 netdev@...r.kernel.org
Cc: Pavel Begunkov <asml.silence@...il.com>, Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jesper Dangaard Brouer <hawk@...nel.org>, David Ahern <dsahern@...nel.org>,
 Mina Almasry <almasrymina@...gle.com>
Subject: Re: [PATCH v1 14/15] io_uring/zcrx: set pp memory provider for an rx
 queue

On 10/7/24 4:16 PM, David Wei wrote:
> From: David Wei <davidhwei@...a.com>
> 
> Set the page pool memory provider for the rx queue configured for zero copy to
> io_uring. Then the rx queue is reset using netdev_rx_queue_restart() and netdev
> core + page pool will take care of filling the rx queue from the io_uring zero
> copy memory provider.
> 
> For now, there is only one ifq so its destruction happens implicitly during
> io_uring cleanup.

Bit wide...

> @@ -237,15 +309,20 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
>  	reg.offsets.tail = offsetof(struct io_uring, tail);
>  
>  	if (copy_to_user(arg, &reg, sizeof(reg))) {
> +		io_close_zc_rxq(ifq);
>  		ret = -EFAULT;
>  		goto err;
>  	}
>  	if (copy_to_user(u64_to_user_ptr(reg.area_ptr), &area, sizeof(area))) {
> +		io_close_zc_rxq(ifq);
>  		ret = -EFAULT;
>  		goto err;
>  	}
>  	ctx->ifq = ifq;
>  	return 0;

Not added in this patch, but since I was looking at rtnl lock coverage,
it's OK to potentially fault while holding this lock? I'm assuming it
is, as I can't imagine any faulting needing to grab it. Not even from
nbd ;-)

Looks fine to me.

-- 
Jens Axboe