linux-kernel - Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2]

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: <17311.1572534953@warthog.procyon.org.uk>
Date:   Thu, 31 Oct 2019 15:15:53 +0000
From:   David Howells <dhowells@...hat.com>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     dhowells@...hat.com, torvalds@...ux-foundation.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        nicolas.dichtel@...nd.com, raven@...maw.net,
        Christian Brauner <christian@...uner.io>,
        keyrings@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-block@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2]

Konstantin Khlebnikov <khlebnikov@...dex-team.ru> wrote:

> Similar synchronization is required for reusing memory after vmsplice()?
> I don't see other way how sender could safely change these pages.

Sounds like a point - if you have multiple parallel contributors to the pipe
via vmsplice(), then FIONREAD is of no use.  To use use FIONREAD, you have to
let the pipe become empty before you can be sure.

David