powerpc/numa: stub out numa_update_cpu_topology()
Previous changes have removed the code which sets bits in cpu_associativity_changes_mask and thus it is never modifed at runtime. From this we can reason that numa_update_cpu_topology() always returns 0 without doing anything. Remove the body of numa_update_cpu_topology() and remove all code which becomes unreachable as a result. Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200612051238.1007764-10-nathanl@linux.ibm.com
This commit is contained in:
Nathan Lynch
Michael Ellerman
parent
9fb8b5fd1b
commit
893ec6461f
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@ -1122,14 +1122,6 @@ u64 memory_hotplug_max(void)
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/* Virtual Processor Home Node (VPHN) support */
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/* Virtual Processor Home Node (VPHN) support */
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#ifdef CONFIG_PPC_SPLPAR
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#ifdef CONFIG_PPC_SPLPAR
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struct topology_update_data {
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struct topology_update_data *next;
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unsigned int cpu;
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int old_nid;
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int new_nid;
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};
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static cpumask_t cpu_associativity_changes_mask;
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static int topology_inited;
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static int topology_inited;
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/*
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/*
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@ -1219,192 +1211,9 @@ int find_and_online_cpu_nid(int cpu)
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return new_nid;
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return new_nid;
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}
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}
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/*
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* Update the CPU maps and sysfs entries for a single CPU when its NUMA
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* characteristics change. This function doesn't perform any locking and is
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* only safe to call from stop_machine().
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*/
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static int update_cpu_topology(void *data)
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{
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struct topology_update_data *update;
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unsigned long cpu;
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if (!data)
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return -EINVAL;
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cpu = smp_processor_id();
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for (update = data; update; update = update->next) {
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int new_nid = update->new_nid;
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if (cpu != update->cpu)
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continue;
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unmap_cpu_from_node(cpu);
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map_cpu_to_node(cpu, new_nid);
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set_cpu_numa_node(cpu, new_nid);
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set_cpu_numa_mem(cpu, local_memory_node(new_nid));
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vdso_getcpu_init();
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}
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return 0;
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}
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static int update_lookup_table(void *data)
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{
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struct topology_update_data *update;
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if (!data)
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return -EINVAL;
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/*
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* Upon topology update, the numa-cpu lookup table needs to be updated
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* for all threads in the core, including offline CPUs, to ensure that
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* future hotplug operations respect the cpu-to-node associativity
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* properly.
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*/
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for (update = data; update; update = update->next) {
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int nid, base, j;
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nid = update->new_nid;
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base = cpu_first_thread_sibling(update->cpu);
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for (j = 0; j < threads_per_core; j++) {
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update_numa_cpu_lookup_table(base + j, nid);
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}
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}
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return 0;
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}
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/*
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* Update the node maps and sysfs entries for each cpu whose home node
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* has changed. Returns 1 when the topology has changed, and 0 otherwise.
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*
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* cpus_locked says whether we already hold cpu_hotplug_lock.
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*/
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int numa_update_cpu_topology(bool cpus_locked)
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int numa_update_cpu_topology(bool cpus_locked)
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{
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{
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unsigned int cpu, sibling, changed = 0;
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return 0;
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struct topology_update_data *updates, *ud;
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cpumask_t updated_cpus;
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struct device *dev;
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int weight, new_nid, i = 0;
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if (topology_inited)
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return 0;
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weight = cpumask_weight(&cpu_associativity_changes_mask);
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if (!weight)
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return 0;
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updates = kcalloc(weight, sizeof(*updates), GFP_KERNEL);
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if (!updates)
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return 0;
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cpumask_clear(&updated_cpus);
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for_each_cpu(cpu, &cpu_associativity_changes_mask) {
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/*
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* If siblings aren't flagged for changes, updates list
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* will be too short. Skip on this update and set for next
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* update.
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*/
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if (!cpumask_subset(cpu_sibling_mask(cpu),
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&cpu_associativity_changes_mask)) {
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pr_info("Sibling bits not set for associativity "
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"change, cpu%d\n", cpu);
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cpumask_or(&cpu_associativity_changes_mask,
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&cpu_associativity_changes_mask,
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cpu_sibling_mask(cpu));
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cpu = cpu_last_thread_sibling(cpu);
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continue;
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}
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new_nid = find_and_online_cpu_nid(cpu);
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if (new_nid == numa_cpu_lookup_table[cpu]) {
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cpumask_andnot(&cpu_associativity_changes_mask,
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&cpu_associativity_changes_mask,
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cpu_sibling_mask(cpu));
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dbg("Assoc chg gives same node %d for cpu%d\n",
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new_nid, cpu);
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cpu = cpu_last_thread_sibling(cpu);
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continue;
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}
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for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
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ud = &updates[i++];
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ud->next = &updates[i];
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ud->cpu = sibling;
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ud->new_nid = new_nid;
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ud->old_nid = numa_cpu_lookup_table[sibling];
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cpumask_set_cpu(sibling, &updated_cpus);
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}
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cpu = cpu_last_thread_sibling(cpu);
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}
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/*
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* Prevent processing of 'updates' from overflowing array
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* where last entry filled in a 'next' pointer.
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*/
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if (i)
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updates[i-1].next = NULL;
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pr_debug("Topology update for the following CPUs:\n");
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if (cpumask_weight(&updated_cpus)) {
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for (ud = &updates[0]; ud; ud = ud->next) {
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pr_debug("cpu %d moving from node %d "
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"to %d\n", ud->cpu,
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ud->old_nid, ud->new_nid);
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}
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}
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/*
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* In cases where we have nothing to update (because the updates list
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* is too short or because the new topology is same as the old one),
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* skip invoking update_cpu_topology() via stop-machine(). This is
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* necessary (and not just a fast-path optimization) since stop-machine
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* can end up electing a random CPU to run update_cpu_topology(), and
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* thus trick us into setting up incorrect cpu-node mappings (since
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* 'updates' is kzalloc()'ed).
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*
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* And for the similar reason, we will skip all the following updating.
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*/
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if (!cpumask_weight(&updated_cpus))
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goto out;
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if (cpus_locked)
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stop_machine_cpuslocked(update_cpu_topology, &updates[0],
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&updated_cpus);
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else
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stop_machine(update_cpu_topology, &updates[0], &updated_cpus);
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/*
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* Update the numa-cpu lookup table with the new mappings, even for
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* offline CPUs. It is best to perform this update from the stop-
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* machine context.
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*/
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if (cpus_locked)
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stop_machine_cpuslocked(update_lookup_table, &updates[0],
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cpumask_of(raw_smp_processor_id()));
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else
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stop_machine(update_lookup_table, &updates[0],
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cpumask_of(raw_smp_processor_id()));
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for (ud = &updates[0]; ud; ud = ud->next) {
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unregister_cpu_under_node(ud->cpu, ud->old_nid);
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register_cpu_under_node(ud->cpu, ud->new_nid);
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dev = get_cpu_device(ud->cpu);
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if (dev)
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kobject_uevent(&dev->kobj, KOBJ_CHANGE);
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cpumask_clear_cpu(ud->cpu, &cpu_associativity_changes_mask);
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changed = 1;
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}
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out:
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kfree(updates);
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return changed;
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}
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}
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int arch_update_cpu_topology(void)
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int arch_update_cpu_topology(void)
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