Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <ab2fabcf-b84d-6850-f25e-edc80a80662a@redhat.com>
Date:   Wed, 2 Feb 2022 12:31:54 -0500
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.4.0
Subject: Re: Aligning tcmalloc with glibc 2.35 rseq ABI
Content-Language: en-US
To:     Florian Weimer <fweimer@redhat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     Chris Kennelly <ckennelly@google.com>,
        Peter Oskolkov <posk@posk.io>,
        Peter Zijlstra <peterz@infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        libc-alpha <libc-alpha@sourceware.org>,
        Paul Turner <pjt@google.com>
References: <432231420.24682.1643727496135.JavaMail.zimbra@efficios.com>
 <CAEE+ybn_Cp1-T=2uB7xJqU2gEU-PxzsaV5jqCOupNp2cx_bK-Q@mail.gmail.com>
 <87mtja1fuz.fsf@oldenburg.str.redhat.com>
 <875ypx1x0d.fsf@oldenburg.str.redhat.com>
 <1375227765.27051.1643801804042.JavaMail.zimbra@efficios.com>
 <770517862.27112.1643807335312.JavaMail.zimbra@efficios.com>
 <87o83pxqh0.fsf@oldenburg.str.redhat.com>
From:   Carlos O'Donell <carlos@redhat.com>
Organization: Red Hat
In-Reply-To: <87o83pxqh0.fsf@oldenburg.str.redhat.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 2/2/22 10:01, Florian Weimer via Libc-alpha wrote:
> * Mathieu Desnoyers:
> 
>> More to the point: is ptrdiff_t the correct type here ? I think so.
>> Do we want to revert the ABI and wait another 6 months before we
>> bring back rseq into glibc just for this ? I'm not sure this limitation
>> justifies it.
>>
>> So if there is a quick way to fix that before the official 2.35 release,
>> I'm all for it, otherwise I cannot say that __rseq_offset being an "int"
>> rather than a "ptrdiff_t" will make much real-life difference (unless
>> I'm proven wrong). But we will be stuck with this quirk forever.
> 
> I'm going to post a patch.  It's fairly small.

I'll review this as glibc release manager for glibc 2.35.

We'll get this right before I cut the release.

-- 
Cheers,
Carlos.