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-calde...@linux.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 <t...@linutronix.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-calde...@linux.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
