On Tue, 10 Feb 2009 19:24:07 +1030 Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > On Thursday 05 February 2009 02:06:36 Andrew Morton wrote: > > On Wed, 4 Feb 2009 21:11:35 +1030 Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > > > > > On Wednesday 04 February 2009 13:31:11 Andrew Morton wrote: > > > > On Wed, 4 Feb 2009 13:14:31 +1030 Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > > > > > I think you're right though: smp_call_function_single (or neat wrappers) > > > > > where possible, work_on_cpu which can fail for the others, and we'll just > > > > > have to plumb in the error returns. > > > > > > > > I bet a lot of those can use plain old schedule_work_on(). > > > > > > Which is where work_on_cpu started: a little wrapper around schedule_work_on. > > > > > > We're going in circles, no? > > > > No, we've made some progress. We have a better understanding of what > > the restrictions, shortcomings and traps are in this stuff. We've > > learned (surprise!) that a one-size-fits-all big hammer wasn't such a > > great idea. > > > > Proposed schedule_work_on() rule: either the flush_work() caller or the > > callback should not hold any explicit or implicit sleeping locks. > > But as you found out looking through these, it's really hard to tell. I can > guess, but that's a little fraught... yup. > How about we make work_on_cpu spawn a temp thread; if you care, use > something cleverer? Spawning a thread just isn't that slow. That's what work_on_cpu-rewrite-it-to-create-a-kernel-thread-on-demand.patch does? > Meanwhile, I'll prepare patches to convert all the non-controversial cases > (ie. smp_call_function-style ones). arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu.patch arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu.patch arch-x86-kernel-cpu-mcheck-mce_amd_64c-avoid-using-work_on_cpu.patch convert three work_on_cpu() callers. The drivers/pci/pci-driver.c one is a bit problematic. I guess as long as we don't find a high frequency set_cpus_allowed() callsite which can't be converted to smp_call_function_single() we'll be OK. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
