linux-kernel - Re: [PATCH net-next v6 12/18] siw: Inline do_tcp

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Message-ID: <38f748a8-be3b-6b64-665c-676805ce3555@talpey.com>
Date:   Tue, 11 Apr 2023 13:22:05 -0400
From:   Tom Talpey <tom@...pey.com>
To:     David Howells <dhowells@...hat.com>, netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Chuck Lever III <chuck.lever@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Bernard Metzler <bmt@...ich.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>, linux-rdma@...r.kernel.org
Subject: Re: [PATCH net-next v6 12/18] siw: Inline do_tcp_sendpages()

On 4/11/2023 12:08 PM, David Howells wrote:
> do_tcp_sendpages() is now just a small wrapper around tcp_sendmsg_locked(),
> so inline it, allowing do_tcp_sendpages() to be removed.  This is part of
> replacing ->sendpage() with a call to sendmsg() with MSG_SPLICE_PAGES set.
> 
> Signed-off-by: David Howells <dhowells@...hat.com>
> Reviewed-by: Bernard Metzler <bmt@...ich.ibm.com>
> cc: Jason Gunthorpe <jgg@...pe.ca>
> cc: Leon Romanovsky <leon@...nel.org>
> cc: Tom Talpey <tom@...pey.com>
> cc: "David S. Miller" <davem@...emloft.net>
> cc: Eric Dumazet <edumazet@...gle.com>
> cc: Jakub Kicinski <kuba@...nel.org>
> cc: Paolo Abeni <pabeni@...hat.com>
> cc: Jens Axboe <axboe@...nel.dk>
> cc: Matthew Wilcox <willy@...radead.org>
> cc: linux-rdma@...r.kernel.org
> cc: netdev@...r.kernel.org
> ---
> 
> Notes:
>      ver #6)
>       - Don't clear MSG_SPLICE_PAGES on the last page.

v6 looks good, thanks.

Reviewed-by: Tom Talpey <tom@...pey.com>


> 
>   drivers/infiniband/sw/siw/siw_qp_tx.c | 17 ++++++++++++-----
>   1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
> index 05052b49107f..5552e60bb927 100644
> --- a/drivers/infiniband/sw/siw/siw_qp_tx.c
> +++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
> @@ -313,7 +313,7 @@ static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
>   }
>   
>   /*
> - * 0copy TCP transmit interface: Use do_tcp_sendpages.
> + * 0copy TCP transmit interface: Use MSG_SPLICE_PAGES.
>    *
>    * Using sendpage to push page by page appears to be less efficient
>    * than using sendmsg, even if data are copied.
> @@ -324,20 +324,27 @@ static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
>   static int siw_tcp_sendpages(struct socket *s, struct page **page, int offset,
>   			     size_t size)
>   {
> +	struct bio_vec bvec;
> +	struct msghdr msg = {
> +		.msg_flags = (MSG_MORE | MSG_DONTWAIT | MSG_SENDPAGE_NOTLAST |
> +			      MSG_SPLICE_PAGES),
> +	};
>   	struct sock *sk = s->sk;
> -	int i = 0, rv = 0, sent = 0,
> -	    flags = MSG_MORE | MSG_DONTWAIT | MSG_SENDPAGE_NOTLAST;
> +	int i = 0, rv = 0, sent = 0;
>   
>   	while (size) {
>   		size_t bytes = min_t(size_t, PAGE_SIZE - offset, size);
>   
>   		if (size + offset <= PAGE_SIZE)
> -			flags = MSG_MORE | MSG_DONTWAIT;
> +			msg.msg_flags &= ~MSG_SENDPAGE_NOTLAST;
>   
>   		tcp_rate_check_app_limited(sk);
> +		bvec_set_page(&bvec, page[i], bytes, offset);
> +		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
> +
>   try_page_again:
>   		lock_sock(sk);
> -		rv = do_tcp_sendpages(sk, page[i], offset, bytes, flags);
> +		rv = tcp_sendmsg_locked(sk, &msg, size);
>   		release_sock(sk);
>   
>   		if (rv > 0) {
> 
>