linux-kernel - Re: [PATCH for 4.16 08/10] membarrier: x86: Provide core serializing command (v3)

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Message-ID: <1443621141.3981.1516130533202.JavaMail.zimbra@efficios.com>
Date:   Tue, 16 Jan 2018 19:22:13 +0000 (UTC)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-api <linux-api@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andrew Hunter <ahh@...gle.com>,
        maged michael <maged.michael@...il.com>,
        Avi Kivity <avi@...lladb.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Dave Watson <davejwatson@...com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrea Parri <parri.andrea@...il.com>,
        "Russell King, ARM Linux" <linux@...linux.org.uk>,
        Greg Hackmann <ghackmann@...gle.com>,
        Will Deacon <will.deacon@....com>,
        David Sehr <sehr@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        x86 <x86@...nel.org>, linux-arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH for 4.16 08/10] membarrier: x86: Provide core
 serializing command (v3)

----- On Jan 16, 2018, at 1:29 PM, Thomas Gleixner tglx@...utronix.de wrote:

> On Mon, 15 Jan 2018, Mathieu Desnoyers wrote:
> 
>> There are two places where core serialization is needed by membarrier:
>> 
>> 1) When returning from the membarrier IPI,
>> 2) After scheduler updates curr to a thread with a different mm, before
>>    going back to user-space, since the curr->mm is used by membarrier to
>>    check whether it needs to send an IPI to that CPU.
> 
> This wants to be split into x86 and core changes. Ideally you make the core
> changes before the previous patch and add the empty inline into
> linux/processor.h....

Good point, done. The first commit introducing the new command now also
introduces the generic stuff moved from the x86 patches.

Thanks,

Mathieu

> 
> Thanks,
> 
> 	tglx

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