linux-kernel - Re: Ctrl+C doesn't interrupt process waiting for I/O

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <48673DAE.6050905@gmail.com>
Date:	Sun, 29 Jun 2008 10:45:50 +0300
From:	Török Edwin <edwintorok@...il.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Avi Kivity <avi@...ranet.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: Ctrl+C doesn't interrupt process waiting for I/O

Jeremy Fitzhardinge wrote:
> Avi Kivity wrote:
>> Applications should not assume that write() (or other syscalls) can't
>> return EINTR.  Not all filesystems have a bounded-time backing store.
>
> The distinction between 'fast' (filesystem) and 'slow' (terminals and
> pipes) blocking syscalls goes back to the earliest days of Unix, and
> is part of the ABI.  Most filesystem syscalls are not documented to
> ever return EINTR.

POSIX documents EINTR for write(), and the manpage on my Linux distro
says the same.
However I don't think introducing EINTR would be beneficial (it will
likely cause applications that don't expect it to break).

>
>> 'soft' has its own problems; namely false positives when someone
>> steps on the network cable, temporarily blocking packet flow, or when
>> using a clustered server which may take some time to recover from a
>> fault.
>
> Sure.  It's the basic problem of trying to make network access
> transparent by hiding the failure modes.  You either need to put up
> with spurious timeouts caused by transient failures, or unbounded
> blocking on real failures.
>
> Regardless, NFS is the exception here, and making normal block-backed
> filesystems start throwing EINTRs around would be a huge behavioural
> change.

Agreed.

Best regards,
--Edwin
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/