linux-kernel - Re: [PATCH net-next v5 11/14] tls/sw: Support MSG_SPLICE

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Message-ID: <20230607101945.65c5df51@kernel.org>
Date:   Wed, 7 Jun 2023 10:19:45 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     David Howells <dhowells@...hat.com>
Cc:     netdev@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Boris Pismenny <borisp@...dia.com>,
        John Fastabend <john.fastabend@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v5 11/14] tls/sw: Support MSG_SPLICE_PAGES

On Wed,  7 Jun 2023 15:05:56 +0100 David Howells wrote:
> +static int tls_sw_sendmsg_splice(struct sock *sk, struct msghdr *msg,
> +				 struct sk_msg *msg_pl, size_t try_to_copy,
> +				 ssize_t *copied)
> +{
> +	struct page *page = NULL, **pages = &page;
> +
> +	do {
> +		ssize_t part;
> +		size_t off;
> +		bool put = false;
> +
> +		part = iov_iter_extract_pages(&msg->msg_iter, &pages,
> +					      try_to_copy, 1, 0, &off);
> +		if (part <= 0)
> +			return part ?: -EIO;
> +
> +		if (WARN_ON_ONCE(!sendpage_ok(page))) {
> +			iov_iter_revert(&msg->msg_iter, part);
> +			return -EIO;
> +		}
> +
> +		sk_msg_page_add(msg_pl, page, part, off);
> +		sk_mem_charge(sk, part);
> +		if (put)
> +			put_page(page);

is put ever set to true?

> +		*copied += part;
> +		try_to_copy -= part;
> +	} while (try_to_copy && !sk_msg_full(msg_pl));
> +
> +	return 0;
> +}
> +
>  int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>  {
>  	long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
> @@ -1020,6 +1052,17 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>  			full_record = true;
>  		}
>  
> +		if (try_to_copy && (msg->msg_flags & MSG_SPLICE_PAGES)) {
> +			ret = tls_sw_sendmsg_splice(sk, msg, msg_pl,
> +						    try_to_copy, &copied);
> +			if (ret < 0)
> +				goto send_end;
> +			tls_ctx->pending_open_record_frags = true;
> +			if (full_record || eor || sk_msg_full(msg_pl))
> +				goto copied;
> +			continue;
> +		}
> +
>  		if (!is_kvec && (full_record || eor) && !async_capable) {
>  			u32 first = msg_pl->sg.end;
>  
> @@ -1082,8 +1125,9 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>  		/* Open records defined only if successfully copied, otherwise
>  		 * we would trim the sg but not reset the open record frags.
>  		 */
> -		tls_ctx->pending_open_record_frags = true;
>  		copied += try_to_copy;
> +copied:
> +		tls_ctx->pending_open_record_frags = true;

Why move pending-open-record-frags setting if it's also set before
jumping?

>  		if (full_record || eor) {
>  			ret = bpf_exec_tx_verdict(msg_pl, sk, full_record,
>  						  record_type, &copied,