netdev - Re: [PATCH net-next v9 11/20] io_uring/zcrx: add io_zcrx

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Message-ID: <CAHS8izNCfQjhmywd=UQgFpk2OQZinnWcz8beZTROzJ33XF55rA@mail.gmail.com>
Date: Mon, 6 Jan 2025 14:46:49 -0800
From: Mina Almasry <almasrymina@...gle.com>
To: David Wei <dw@...idwei.uk>
Cc: io-uring@...r.kernel.org, netdev@...r.kernel.org, 
	Jens Axboe <axboe@...nel.dk>, 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>, 
	Stanislav Fomichev <stfomichev@...il.com>, Joe Damato <jdamato@...tly.com>, 
	Pedro Tammela <pctammela@...atatu.com>
Subject: Re: [PATCH net-next v9 11/20] io_uring/zcrx: add io_zcrx_area

On Tue, Dec 17, 2024 at 4:38 PM David Wei <dw@...idwei.uk> wrote:
>
> Add io_zcrx_area that represents a region of userspace memory that is
> used for zero copy. During ifq registration, userspace passes in the
> uaddr and len of userspace memory, which is then pinned by the kernel.
> Each net_iov is mapped to one of these pages.
>
> The freelist is a spinlock protected list that keeps track of all the
> net_iovs/pages that aren't used.
>

FWIW we devmem uses genpool to manage the freelist and that lets us do
allocations/free without locks. Not saying you should migrate to that
but it's an option you have available.

-- 
Thanks,
Mina