static int __smp_rescan_cpus(void)
{
cpumask_t avail;
cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
if (smp_use_sigp_detection)
return smp_rescan_cpus_sigp(avail);
else
return smp_rescan_cpus_sclp(avail);
}
/*
* Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle
* here is that a cpu device node may represent up to two logical cpus
* in the SMT case. We must honor the assumption in other code that
* the logical ids for sibling SMT threads x and y are adjacent, such
* that x^1 == y and y^1 == x.
*/
static int pseries_add_processor(struct device_node *np)
{
unsigned int cpu;
cpumask_var_t candidate_mask, tmp;
int err = -ENOSPC, len, nthreads, i;
const __be32 *intserv;
intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
if (!intserv)
return 0;
zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
zalloc_cpumask_var(&tmp, GFP_KERNEL);
nthreads = len / sizeof(u32);
for (i = 0; i < nthreads; i++)
cpumask_set_cpu(i, tmp);
cpu_maps_update_begin();
BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));
/* Get a bitmap of unoccupied slots. */
cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
if (cpumask_empty(candidate_mask)) {
/* If we get here, it most likely means that NR_CPUS is
* less than the partition's max processors setting.
*/
printk(KERN_ERR "Cannot add cpu %pOF; this system configuration"
" supports %d logical cpus.\n", np,
num_possible_cpus());
goto out_unlock;
}
while (!cpumask_empty(tmp))
if (cpumask_subset(tmp, candidate_mask))
/* Found a range where we can insert the new cpu(s) */
break;
else
cpumask_shift_left(tmp, tmp, nthreads);
if (cpumask_empty(tmp)) {
printk(KERN_ERR "Unable to find space in cpu_present_mask for"
" processor %s with %d thread(s)\n", np->name,
nthreads);
goto out_unlock;
}
for_each_cpu(cpu, tmp) {
BUG_ON(cpu_present(cpu));
set_cpu_present(cpu, true);
set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
}
