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

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Message-ID: <995fc335-47f5-6884-eaee-283ad81e28b7@suse.com>
Date:   Tue, 30 Oct 2018 14:50:27 +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 30/10/2018 14:33, Marc Dionne wrote:
> On Mon, Oct 29, 2018 at 11:25 AM Juergen Gross <jgross@...e.com> wrote:
>>
>> 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
> 
> Thanks for the quick patch.  Does this also need fixing for arm/arm64?
> I can't easily verify but it seems like it would have the same issue.

pv_lock_ops was x86 only.


Juergen