On Sat, 2006-03-18 at 06:09 -0800, Ashok Raj wrote:
> On Fri, Mar 17, 2006 at 07:43:22PM +0530, Srivatsa Vaddagiri wrote:
> > On Fri, Mar 17, 2006 at 01:04:12AM -0800, Andrew Morton wrote:
> > > OK.. I guess we should fix those architectures while we're thinking about it.
> >
> > Only x86 has this bug, so only x86 needs to be fixed. Neverthless
> > Ashok's patch [1] should address all architectures that may implement
> > smp_prepare_cpu() in future as well.
> >
> Hi Vatsa
>
> Since smp_prepare_cpu was introduced only to work around warm-boot on i386 due to the
> strange kickstart process of AP's. I have moved this al-together within __cpu_up()
> i386 arch code, so its less confusing to other arch's that have done it right already.
>
> Here is the updated patch, it removes smp_prepare_cpu() from being called from generic
> core cpuhotplug code, and moved it to i386 side.
>
> I did some basic up/down testing on a 2 way PIII box.
>
> Shaohua, could you take a look at this code, and also check suspend/resume is not
> affected?
>
> Andrew, could we queue it to -mm for some exposure before inclusion.
>
> thanks
>
> --
> Cheers,
> Ashok Raj
> - Open Source Technology Center
>
>
> Check if cpu can be onlined before calling smp_prepare_cpu()
>
> - Moved check for online cpu out of smp_prepare_cpu()
> - Moved default declaration of smp_prepare_cpu() to kernel/cpu.c
> - Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
> its called from cpu_up() as well now.
> - Removed clearing from cpu_present_map during cpu_offline as it breaks using cpu_up()
> directly during a subsequent online operation.
>
> Signed-off-by: Ashok Raj <[email protected]>
> --------------------------------------------------------
> arch/i386/kernel/smpboot.c | 21 +++++++++++++++++----
> drivers/base/cpu.c | 9 +--------
> include/linux/cpu.h | 1 -
> kernel/power/smp.c | 4 +---
> 4 files changed, 19 insertions(+), 16 deletions(-)
>
> Index: linux-2.6.16-rc6-mm1/arch/i386/kernel/smpboot.c
> ===================================================================
> --- linux-2.6.16-rc6-mm1.orig/arch/i386/kernel/smpboot.c
> +++ linux-2.6.16-rc6-mm1/arch/i386/kernel/smpboot.c
> @@ -1002,7 +1002,6 @@ void cpu_exit_clear(void)
>
> cpu_clear(cpu, cpu_callout_map);
> cpu_clear(cpu, cpu_callin_map);
> - cpu_clear(cpu, cpu_present_map);
>
> cpu_clear(cpu, smp_commenced_mask);
> unmap_cpu_to_logical_apicid(cpu);
> @@ -1021,14 +1020,13 @@ static void __devinit do_warm_boot_cpu(v
> complete(info->complete);
> }
>
> -int __devinit smp_prepare_cpu(int cpu)
> +static int __devinit __smp_prepare_cpu(int cpu)
> {
> DECLARE_COMPLETION(done);
> struct warm_boot_cpu_info info;
> struct work_struct task;
> int apicid, ret;
>
> - lock_cpu_hotplug();
> apicid = x86_cpu_to_apicid[cpu];
> if (apicid == BAD_APICID) {
> ret = -ENODEV;
> @@ -1053,7 +1051,6 @@ int __devinit smp_prepare_cpu(int cpu)
> zap_low_mappings();
> ret = 0;
> exit:
> - unlock_cpu_hotplug();
> return ret;
> }
> #endif
> @@ -1379,6 +1376,22 @@ void __cpu_die(unsigned int cpu)
>
> int __devinit __cpu_up(unsigned int cpu)
> {
> + int ret=0;
> +
> +#ifdef CONFIG_HOTPLUG_CPU
> + /*
> + * We do warm boot only on cpus that had booted earlier
> + * Otherwise cold boot is all handled from smp_boot_cpus().
> + * cpu_callin_map is set during AP kickstart process. Its reset
> + * when a cpu is taken offline from cpu_exit_clear().
> + */
> + if (!cpu_isset(cpu, cpu_callin_map))
> + ret = __smp_prepare_cpu(cpu);
Does this work for boot time? cpu_callin_map isn't set at boot time for
APs.
Thanks,
Shaohua
-
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