linux-kernel - Re: [PATCH] x86/alternatives: free smp_alt

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Message-ID: <59F2EA25.1080903@huawei.com>
Date:   Fri, 27 Oct 2017 16:11:17 +0800
From:   zhouchengming <zhouchengming1@...wei.com>
To:     Borislav Petkov <bp@...e.de>
CC:     <mingo@...hat.com>, <tglx@...utronix.de>, <peterz@...radead.org>,
        <hpa@...or.com>, <jkosina@...e.cz>, <rostedt@...dmis.org>,
        <mjurczyk@...gle.com>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/alternatives: free smp_alt_modules when enable smp

On 2017/10/27 15:49, Borislav Petkov wrote:
> On Fri, Oct 27, 2017 at 03:18:12PM +0800, Zhou Chengming wrote:
>> In the current code, we don't free smp_alt_modules when enable smp,
>> so have to wait module unload to call alternatives_smp_module_del()
>> to free its smp_alt_module. This strategy has shortcomings.
> I love it when the commit message states there is allegedly some problem
> but it doesn't explain what that problem is.

Well, I should explain it although it's small shortcomings. First, maybe
some modules don't unload after smp enabled, so these smp_alt_modules won't
be freed even they are useless anymore. Second, every module has to call
alternatives_smp_module_del() when unload to see if it's in the list even
after smp enabled, it's complete useless work. So why not take the quick
way like we do in alternatives_smp_module_add() ?

Thanks.

> > From the looks of the patch, though, I'd prefer what we do now and not
> touch the code.
>