linux-kernel - Re: x86/paravirt: Use a single ops structure

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Date:   Mon, 29 Oct 2018 15:24:50 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Marc Dionne <marc.dionne@...istor.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: x86/paravirt: Use a single ops structure

On 29/10/2018 13:58, Marc Dionne wrote:
> On Tue, Oct 23, 2018 at 2:37 PM Linux Kernel Mailing List
> <linux-kernel@...r.kernel.org> wrote:
>>
>> Commit:     5c83511bdb9832c86be20fb86b783356e2f58062
>> Parent:     27876f3882fdd4acb3d3614a0133ecdc777fc292
>> Refname:    refs/heads/master
>> Web:        https://git.kernel.org/torvalds/c/5c83511bdb9832c86be20fb86b783356e2f58062
>> Author:     Juergen Gross <jgross@...e.com>
>> AuthorDate: Tue Aug 28 09:40:19 2018 +0200
>> Committer:  Thomas Gleixner <tglx@...utronix.de>
>> CommitDate: Mon Sep 3 16:50:35 2018 +0200
>>
>>     x86/paravirt: Use a single ops structure
>>
>>     Instead of using six globally visible paravirt ops structures combine
>>     them in a single structure, keeping the original structures as
>>     sub-structures.
>>
>>     This avoids the need to assemble struct paravirt_patch_template at
>>     runtime on the stack each time apply_paravirt() is being called (i.e.
>>     when loading a module).
> 
> The above commit replaces pv_lock_ops, which was EXPORT_SYMBOL, with
> something that is part of pv_ops, which is EXPORT_SYMBOL_GPL.    When
> CONFIG_PARAVIRT_SPINLOCKS is set, this has the side effect of making
> spin_lock() unusable by out of tree modules, which will likely be an
> issue for many, if not most of them.

Thanks for noticing!

Sending a patch soon...


Juergen