Messages in this thread | | | Subject | Re: [PATCH] Check for online cpus before bringing them up | From | Shaohua Li <> | Date | Tue, 21 Mar 2006 09:08:05 +0800 |
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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 <ashok.raj@intel.com> > -------------------------------------------------------- > 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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