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
| ||
|
Date: Thu, 14 Jun 2018 19:21:12 -0700 From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> To: Nicholas Piggin <npiggin@...il.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <andi.kleen@...el.com>, Ashok Raj <ashok.raj@...el.com>, Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>, "Ravi V. Shankar" <ravi.v.shankar@...el.com>, x86@...nel.org, sparclinux@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, Jacob Pan <jacob.jun.pan@...el.com>, Don Zickus <dzickus@...hat.com>, Michael Ellerman <mpe@...erman.id.au>, Frederic Weisbecker <frederic@...nel.org>, Babu Moger <babu.moger@...cle.com>, "David S. Miller" <davem@...emloft.net>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Masami Hiramatsu <mhiramat@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Philippe Ombredanne <pombredanne@...b.com>, Colin Ian King <colin.king@...onical.com>, "Luis R. Rodriguez" <mcgrof@...nel.org>, iommu@...ts.linux-foundation.org Subject: Re: [RFC PATCH 12/23] kernel/watchdog: Introduce a struct for NMI watchdog operations On Thu, Jun 14, 2018 at 12:32:50PM +1000, Nicholas Piggin wrote: > On Wed, 13 Jun 2018 18:31:17 -0700 > Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> wrote: > > > On Wed, Jun 13, 2018 at 09:52:25PM +1000, Nicholas Piggin wrote: > > > On Wed, 13 Jun 2018 11:26:49 +0200 (CEST) > > > Thomas Gleixner <tglx@...utronix.de> wrote: > > > > > > > On Wed, 13 Jun 2018, Peter Zijlstra wrote: > > > > > On Wed, Jun 13, 2018 at 05:41:41PM +1000, Nicholas Piggin wrote: > > > > > > On Tue, 12 Jun 2018 17:57:32 -0700 > > > > > > Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> wrote: > > > > > > > > > > > > > Instead of exposing individual functions for the operations of the NMI > > > > > > > watchdog, define a common interface that can be used across multiple > > > > > > > implementations. > > > > > > > > > > > > > > The struct nmi_watchdog_ops is defined for such operations. These initial > > > > > > > definitions include the enable, disable, start, stop, and cleanup > > > > > > > operations. > > > > > > > > > > > > > > Only a single NMI watchdog can be used in the system. The operations of > > > > > > > this NMI watchdog are accessed via the new variable nmi_wd_ops. This > > > > > > > variable is set to point the operations of the first NMI watchdog that > > > > > > > initializes successfully. Even though at this moment, the only available > > > > > > > NMI watchdog is the perf-based hardlockup detector. More implementations > > > > > > > can be added in the future. > > > > > > > > > > > > Cool, this looks pretty nice at a quick glance. sparc and powerpc at > > > > > > least have their own NMI watchdogs, it would be good to have those > > > > > > converted as well. > > > > > > > > > > Yeah, agreed, this looks like half a patch. > > > > > > > > Though I'm not seeing the advantage of it. That kind of NMI watchdogs are > > > > low level architecture details so having yet another 'ops' data structure > > > > with a gazillion of callbacks, checks and indirections does not provide > > > > value over the currently available weak stubs. > > > > > > The other way to go of course is librify the perf watchdog and make an > > > x86 watchdog that selects between perf and hpet... I also probably > > > prefer that for code such as this, but I wouldn't strongly object to > > > ops struct if I'm not writing the code. It's not that bad is it? > > > > My motivation to add the ops was that the hpet and perf watchdog share > > significant portions of code. > > Right, a good motivation. > > > I could look into creating the library for > > common code and relocate the hpet watchdog into arch/x86 for the hpet- > > specific parts. > > If you can investigate that approach, that would be appreciated. I hope > I did not misunderstand you there, Thomas. > > Basically you would have perf infrastructure and hpet infrastructure, > and then the x86 watchdog driver will use one or the other of those. The > generic watchdog driver will be just a simple shim that uses the perf > infrastructure. Then hopefully the powerpc driver would require almost > no change. Sure, I will try to structure code to minimize the changes to the powerpc watchdog... without breaking the sparc one. Thanks and BR, Ricardo
Powered by blists - more mailing lists