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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 24 Oct 2019 17:29:51 -0400
Message-ID: <CAHk-=wiMho2AhcTWC3-3zGK7639XL9UT=AheMXY0pxGHDACn6g@mail.gmail.com>
Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2]
To:     David Howells <dhowells@redhat.com>
Cc:     Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>, raven@themaw.net,
        Christian Brauner <christian@brauner.io>,
        keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-block <linux-block@vger.kernel.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Thu, Oct 24, 2019 at 12:57 PM David Howells <dhowells@redhat.com> wrote:
>
> pipe: Add fsync() support
>
> The keyrings testsuite needs the ability to wait for all the outstanding
> notifications in the queue to have been processed so that it can then go
> through them to find out whether the notifications it expected have been
> emitted.

Can't you just do

    ioctl(fd, FIONREAD, &count);

in a loop instead? "No paperwork. Just sprinkle some msleep() crack on
him, and let's get out of here"

               Linus