Messages in this thread | | | Date | Mon, 28 Sep 2015 09:57:14 +0800 | From | Tang Chen <> | Subject | Re: [PATCH v2 5/7] x86, acpi, cpu-hotplug: Introduce apicid_to_cpuid[] array to store persistent cpuid <-> apicid mapping. |
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On 09/27/2015 01:56 AM, Tejun Heo wrote: > On Sat, Sep 26, 2015 at 05:52:09PM +0800, Tang Chen wrote: >>>> +static int allocate_logical_cpuid(int apicid) >>>> +{ >>>> + int i; >>>> + >>>> + /* >>>> + * cpuid <-> apicid mapping is persistent, so when a cpu is up, >>>> + * check if the kernel has allocated a cpuid for it. >>>> + */ >>>> + for (i = 0; i < max_logical_cpuid; i++) { >>>> + if (cpuid_to_apicid[i] == apicid) >>>> + return i; >>>> + } >>>> + >>>> + /* Allocate a new cpuid. */ >>>> + if (max_logical_cpuid >= nr_cpu_ids) { >>>> + WARN_ONCE(1, "Only %d processors supported." >>>> + "Processor %d/0x%x and the rest are ignored.\n", >>>> + nr_cpu_ids - 1, max_logical_cpuid, apicid); >>>> + return -1; >>>> + } >>> So, the original code didn't have this failure mode, why is this >>> different for the new code? >> It is not different. Since max_logical_cpuid is new, this is ensure it won't >> go beyond NR_CPUS. > If the above condition can happen, the original code should have had a > similar check as above, right? Sure, max_logical_cpuid is a new thing > but that doesn't seem to change whether the above condition can happen > or not, no?
Right, indeed. It is in
generic_processor_info() |--> if (num_processors >= nr_cpu_ids)
Will remove my new added check.
Thanks.
> > Thanks. >
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