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]
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