linux-kernel - Re: [PATCHv7 01/33] ns: Introduce Time Namespace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5f4c2f29-ca68-b19c-017f-d23730f6e871@arm.com>
Date:   Wed, 16 Oct 2019 11:44:38 +0100
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Andrei Vagin <avagin@...nvz.org>,
        Adrian Reber <adrian@...as.de>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jann Horn <jannh@...gle.com>, Jeff Dike <jdike@...toit.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Shuah Khan <shuah@...nel.org>,
        containers@...ts.linux-foundation.org, criu@...nvz.org,
        linux-api@...r.kernel.org, x86@...nel.org,
        Andrei Vagin <avagin@...il.com>
Subject: Re: [PATCHv7 01/33] ns: Introduce Time Namespace


On 10/16/19 11:39 AM, Thomas Gleixner wrote:
> On Wed, 16 Oct 2019, Vincenzo Frascino wrote:
> 
> < Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >
> 
>>> --- a/init/Kconfig
>>> +++ b/init/Kconfig
>>> @@ -1096,6 +1096,13 @@ config UTS_NS
>>>  	  In this namespace tasks see different info provided with the
>>>  	  uname() system call
>>>  
>>> +config TIME_NS
>>> +	bool "TIME namespace"
>>> +	default y
>>
>> Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
>> the architectures that have no support for time namespaces.
>> The direct consequence is that the fallbacks defined in this patch are never
>> selected and this ends up in kernel compilation errors due to missing symbols.
>>
>> The error below shows what happens on arm64 (similar behavior on other
>> architectures):
>>
>> aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
>> kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'
>>
>> My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
>> architectures that enable time namespaces select it and make CONFIG_TIME_NS
>> select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.
> 
> Nah.
> 
> config TIME_NS
> 	bool "TIME namespace"
> 	depends on GENERIC_VDSO_TIME_NS
> 	default y
> 
> and in lib/vdso/Kconfig
> 
> config GENERIC_VDSO_TIME_NS
> 	bool
> 
> and let architectures which have support for the VDSO bits select it.
>

Agreed, this is even better.

> < Trim another gazillion of useless lines >
> 
> See: https://people.kernel.org/tglx/notes-about-netiquette
> 
> Thanks,
> 
> 	tglx
> 

-- 
Regards,
Vincenzo