2014-10-13 05:16:19

by Rusty Russell

[permalink] [raw]
Subject: Re: [RFC PATCH 0/2] kmod: Support lockup option to make module un-removable

Lucas De Marchi <[email protected]> writes:
> On Tue, Aug 26, 2014 at 9:04 AM, Masami Hiramatsu
> <[email protected]> wrote:
>> Hi,
>>
>> Here is a pair of patches which adds --lockup option to
>> modprobe and libkmod.
>>
>> As I sent a series of patches which removes stop_machine()
>> from module removal: https://lkml.org/lkml/2014/8/25/142
>> it also adds lockup option which lock up the module in
>> the kernel and makes it un-removable.
>>
>> These patches enables us to use that option when loading
>> modules. Module lockup may be good for BIG SMP machines
>> since the kernel skips module refcounting if the module
>> is locked up :)
>>
>> Anyway, this is not needed if the lockup option is dropped
>> from the series. I send this for testing.
>
> Ok. I'm not sure it's clear... I'm waiting for feedback on the kernel
> patches in order to proceed with any review here. I'm not really
> convinced we want this option when loading a module.
>
> Rusty, what do you think?

I'm not convinced, I asked him to drop that patch. If we have
significant performance issues, we'll have to do something smarter I
think anyway.

Cheers,
Rusty.