From: "H. Peter Anvin" <hpa@zytor.com>
To: Ulrich Drepper <drepper@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: sendfile and EAGAIN
Date: Sat, 02 Mar 2013 19:53:47 -0800 [thread overview]
Message-ID: <5132C94B.5090701@zytor.com> (raw)
In-Reply-To: <CAOPLpQcs5GgVRqXhnxF0Ui0k-39-xX5N2nYWYY4DhVWMYCMQ7w@mail.gmail.com>
On 02/25/2013 09:22 AM, Ulrich Drepper wrote:
> When using sendfile with a non-blocking output file descriptor for a
> socket the operation can cause a partial write because of capacity
> issues. This is nothing critical and the operation could resume after
> the output queue is cleared. The problem is: there is no way to
> determine where to resume.
>
> The system call just returns -EAGAIN without any further indication.
> The caller doesn't know what to resend.
This is IMO just a bug. EAGAIN should only be used in the zero-byte
case and in other cases it should return the number of bytes
transferred, just like all the read/write system calls.
This was clearly also the intent.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
prev parent reply other threads:[~2013-03-03 3:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-25 17:22 sendfile and EAGAIN Ulrich Drepper
2013-02-25 19:22 ` Eric Dumazet
2013-03-03 1:41 ` Ulrich Drepper
2013-03-03 3:09 ` Eric Dumazet
2013-03-03 3:16 ` Ulrich Drepper
2013-03-04 10:28 ` Eric Wong
2013-03-05 0:11 ` Ulrich Drepper
2013-03-03 3:53 ` H. Peter Anvin [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5132C94B.5090701@zytor.com \
--to=hpa@zytor.com \
--cc=drepper@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.