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?
Thanks.
--
tejun
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