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Date: Tue, 2 Jul 2024 09:01:37 -0600
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Subject: Re: [PATCH net-next v15 11/14] net: add SO_DEVMEM_DONTNEED setsockopt
 to release RX frags
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To: Mina Almasry <almasrymina@google.com>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
 linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org,
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Cc: "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Donald Hunter <donald.hunter@gmail.com>,
 Jonathan Corbet <corbet@lwn.net>,
 Richard Henderson <richard.henderson@linaro.org>,
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 <mattst88@gmail.com>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
 "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
 Helge Deller <deller@gmx.de>, Andreas Larsson <andreas@gaisler.com>,
 Jesper Dangaard Brouer <hawk@kernel.org>,
 Ilias Apalodimas <ilias.apalodimas@linaro.org>,
 Steven Rostedt <rostedt@goodmis.org>, Masami Hiramatsu
 <mhiramat@kernel.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
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 Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>,
 Martin KaFai Lau <martin.lau@linux.dev>, Eduard Zingerman
 <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
 Yonghong Song <yonghong.song@linux.dev>,
 John Fastabend <john.fastabend@gmail.com>, KP Singh <kpsingh@kernel.org>,
 Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
 Jiri Olsa <jolsa@kernel.org>, Steffen Klassert
 <steffen.klassert@secunet.com>, Herbert Xu <herbert@gondor.apana.org.au>,
 Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
 Shuah Khan <shuah@kernel.org>, Sumit Semwal <sumit.semwal@linaro.org>,
 =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
 Bagas Sanjaya <bagasdotme@gmail.com>, Christoph Hellwig <hch@infradead.org>,
 Nikolay Aleksandrov <razor@blackwall.org>,
 Pavel Begunkov <asml.silence@gmail.com>, David Wei <dw@davidwei.uk>,
 Jason Gunthorpe <jgg@ziepe.ca>, Yunsheng Lin <linyunsheng@huawei.com>,
 Shailend Chand <shailend@google.com>,
 Harshitha Ramamurthy <hramamurthy@google.com>,
 Shakeel Butt <shakeel.butt@linux.dev>, Jeroen de Borst
 <jeroendb@google.com>, Praveen Kaligineedi <pkaligineedi@google.com>,
 Willem de Bruijn <willemb@google.com>, Kaiyuan Zhang <kaiyuanz@google.com>
References: <20240628003253.1694510-1-almasrymina@google.com>
 <20240628003253.1694510-12-almasrymina@google.com>
From: David Ahern <dsahern@kernel.org>
In-Reply-To: <20240628003253.1694510-12-almasrymina@google.com>
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On 6/27/24 6:32 PM, Mina Almasry wrote:
> @@ -1049,6 +1050,62 @@ static int sock_reserve_memory(struct sock *sk, int bytes)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PAGE_POOL
> +static noinline_for_stack int
> +sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen)
> +{
> +	unsigned int num_tokens, i, j, k, netmem_num = 0;
> +	struct dmabuf_token *tokens;
> +	netmem_ref netmems[16];
> +	int ret = 0;
> +
> +	if (sk->sk_type != SOCK_STREAM || sk->sk_protocol != IPPROTO_TCP)
> +		return -EBADF;
> +
> +	if (optlen % sizeof(struct dmabuf_token) ||
> +	    optlen > sizeof(*tokens) * 128)
> +		return -EINVAL;
> +
> +	tokens = kvmalloc_array(128, sizeof(*tokens), GFP_KERNEL);

The '128' should be a named macro with a comment on why that value.