linux-kernel - Re: Restartable Sequences system call merged into Linux

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Message-ID: <422468177.14427.1529085017684.JavaMail.zimbra@efficios.com>
Date:   Fri, 15 Jun 2018 13:50:17 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Florian Weimer <fweimer@...hat.com>
Cc:     Pavel Machek <pavel@....cz>, carlos <carlos@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        libc-alpha <libc-alpha@...rceware.org>
Subject: Re: Restartable Sequences system call merged into Linux

----- On Jun 15, 2018, at 1:09 AM, Florian Weimer fweimer@...hat.com wrote:

> On 06/14/2018 03:01 PM, Mathieu Desnoyers wrote:
>> Another alternative would be to somehow let glibc handle the registration,
>> perhaps only doing it for applications expressing their interest for rseq.
> 
> That's not really possible.  We can't rely on the visibility of symbol
> bindings due to lazy binding and hidden visibility.  Registration of
> intent by other means will not work because if it is done from user
> code, some other library may have already launched a thread at this point.
> 
> (It's also a moot point if we want to use restartable sequences in glibc
> itself.)

Considering that we can expect the glibc memory allocator to benefit from
rseq to speed up its memory allocator, this means pretty much any application
linked against glibc *will* end up using rseq indirectly.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com