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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 2 Jun 2023 07:28:05 -0400
Message-ID: <CAHk-=wjvgL5nyZmpYRWBfab4NKvfQ7NjUvUhE3a3wYTyTEHdfQ@mail.gmail.com>
Subject: Re: Bug in short splice to socket?
To:     David Howells <dhowells@redhat.com>
Cc:     Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Chuck Lever <chuck.lever@oracle.com>,
        Boris Pismenny <borisp@nvidia.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Christoph Hellwig <hch@infradead.org>
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On Fri, Jun 2, 2023 at 4:23=E2=80=AFAM David Howells <dhowells@redhat.com> =
wrote:
>
> +/*
> + * Pass a zero-length record to the splice-write actor with SPLICE_F_MOR=
E
> + * turned off to allow the network to see MSG_MORE deasserted.
> + */
> +static ssize_t splice_from_pipe_zero(struct pipe_inode_info *pipe,

David, STOP.

Stop doing these crazy hacks to generic splice code. None of this makes sen=
se.

Those zero-sized splices have never worked, don't try to make them work.

The splice() system call has always had that

        if (!len)
                return 0;

since being introduced. We're not adding any crazy stuff now.

Do what I already suggested: making SPLICE_F_MORE reflect reality.

Or don't do anything at all. Because this kind of hacky garbage is not
even amusing.

               Linus