linux-kernel - Re: [PATCH v2 0/2] make POSIX timers optional

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]

Date:   Tue, 20 Sep 2016 18:47:02 -0400 (EDT)
From:   Nicolas Pitre <nicolas.pitre@...aro.org>
To:     Thomas Gleixner <tglx@...utronix.de>
cc:     Richard Cochran <richardcochran@...il.com>,
        John Stultz <john.stultz@...aro.org>,
        Josh Triplett <josh@...htriplett.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] make POSIX timers optional

On Tue, 20 Sep 2016, Thomas Gleixner wrote:

> I think the whole approach is wrong because it makes the PTP split at the
> wrong level.
> 
> Currently we have:
> 
> 	  DRIVER_X
> 	  tristate "Driver X"
> 	  select PTP
> 
> In order to make POSIX_CLOCK configurable we should have
> 
>        	  PTP
> 	  tristate "PTP"
> 	  select POSIX_CLOCK
> 
> Now if you want to distangle PTP from a driver then you split it at the
> driver level and not at the PTP level:
> 
>       	  DRIVER_X
> 	  tristate "Driver X"
> 
> 	  DRIVER_X_PTP
> 	  bool "Enable PTP support"
> 	  default y if !MAKE_IT_TINY
> 	  depends on DRIVER_X
> 	  select PTP
> 
> We have already drivers following that scheme. That way you make the PTP
> support in the driver conditional on DRIVER_X_PTP and have no hassle with
> modules and dependencies.

I beg to disagree.

There are way more drivers than subsystems and if you had to go around 
unselecting all NIC drivers for CONFIG_ETHERNET to be turned off, and 
with CONFIG_ETHERNET=n you'd finally be able to turn networking off, 
then this would be a nightmare.

IMHO it is much nicer for the poor user configuring the kernel to have a 
single configuration prompt for PTP support, and then have whatever 
driver that can provide a PTP clock just do it (or omit it) based on 
that single prompt.  Prompting for PTP support for each individual 
ethernet driver is silly.

Nicolas