[PATCH 05/17] all: replace cpumask_weight with cpumask_empty where appropriate

Yury Norov
2021-12-18T21:21:16Z

In many cases, kernel code calls cpumask_weight() to check if any bit of
a given cpumask is set. We can do it more efficiently with cpumask_empty()
because cpumask_empty() stops traversing the cpumask as soon as it finds
first set bit, while cpumask_weight() counts all bits unconditionally.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
arch/alpha/kernel/process.c | 2 +-
arch/ia64/kernel/setup.c | 2 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 14 +++++++-------
arch/x86/mm/mmio-mod.c | 2 +-
arch/x86/platform/uv/uv_nmi.c | 2 +-
drivers/cpufreq/qcom-cpufreq-hw.c | 2 +-
drivers/cpufreq/scmi-cpufreq.c | 2 +-
drivers/gpu/drm/i915/i915_pmu.c | 2 +-
drivers/infiniband/hw/hfi1/affinity.c | 4 ++--
drivers/irqchip/irq-bcm6345-l1.c | 2 +-
kernel/irq/affinity.c | 2 +-
kernel/padata.c | 2 +-
kernel/rcu/tree_nocb.h | 4 ++--
kernel/rcu/tree_plugin.h | 2 +-
kernel/sched/core.c | 2 +-
kernel/sched/topology.c | 2 +-
kernel/time/clocksource.c | 2 +-
mm/vmstat.c | 4 ++--
18 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index f4759e4ee4a9..a4415ad44982 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -125,7 +125,7 @@ common_shutdown_1(void *generic_ptr)
/* Wait for the secondaries to halt. */
set_cpu_present(boot_cpuid, false);
set_cpu_possible(boot_cpuid, false);
- while (cpumask_weight(cpu_present_mask))
+ while (!cpumask_empty(cpu_present_mask))
barrier();
#endif

diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 5010348fa21b..fd6301eafa9d 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -572,7 +572,7 @@ setup_arch (char **cmdline_p)
#ifdef CONFIG_ACPI_HOTPLUG_CPU
prefill_possible_map();
#endif
- per_cpu_scan_finalize((cpumask_weight(&early_cpu_possible_map) == 0 ?
+ per_cpu_scan_finalize((cpumask_empty(&early_cpu_possible_map) ?
32 : cpumask_weight(&early_cpu_possible_map)),
additional_cpus > 0 ? additional_cpus : 0);
#endif /* CONFIG_ACPI_NUMA */
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b57b3db9a6a7..e23ff03290b8 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -341,14 +341,14 @@ static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,

/* Check whether cpus belong to parent ctrl group */
cpumask_andnot(tmpmask, newmask, &prgrp->cpu_mask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
rdt_last_cmd_puts("Can only add CPUs to mongroup that belong to parent\n");
return -EINVAL;
}

/* Check whether cpus are dropped from this group */
cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
/* Give any dropped cpus to parent rdtgroup */
cpumask_or(&prgrp->cpu_mask, &prgrp->cpu_mask, tmpmask);
update_closid_rmid(tmpmask, prgrp);
@@ -359,7 +359,7 @@ static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
* and update per-cpu rmid
*/
cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
head = &prgrp->mon.crdtgrp_list;
list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
if (crgrp == rdtgrp)
@@ -394,7 +394,7 @@ static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,

/* Check whether cpus are dropped from this group */
cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
/* Can't drop from default group */
if (rdtgrp == &rdtgroup_default) {
rdt_last_cmd_puts("Can't drop CPUs from default group\n");
@@ -413,12 +413,12 @@ static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
* and update per-cpu closid/rmid.
*/
cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
if (r == rdtgrp)
continue;
cpumask_and(tmpmask1, &r->cpu_mask, tmpmask);
- if (cpumask_weight(tmpmask1))
+ if (!cpumask_empty(tmpmask1))
cpumask_rdtgrp_clear(r, tmpmask1);
}
update_closid_rmid(tmpmask, rdtgrp);
@@ -488,7 +488,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,

/* check that user didn't specify any offline cpus */
cpumask_andnot(tmpmask, newmask, cpu_online_mask);
- if (cpumask_weight(tmpmask)) {
+ if (!cpumask_empty(tmpmask)) {
ret = -EINVAL;
rdt_last_cmd_puts("Can only assign online CPUs\n");
goto unlock;
diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index 933a2ebad471..c3317f0650d8 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -400,7 +400,7 @@ static void leave_uniprocessor(void)
int cpu;
int err;

- if (!cpumask_available(downed_cpus) || cpumask_weight(downed_cpus) == 0)
+ if (!cpumask_available(downed_cpus) || cpumask_empty(downed_cpus))
return;
pr_notice("Re-enabling CPUs...\n");
for_each_cpu(cpu, downed_cpus) {
diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index 1e9ff28bc2e0..ea277fc08357 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -985,7 +985,7 @@ static int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)

/* Clear global flags */
if (master) {
- if (cpumask_weight(uv_nmi_cpu_mask))
+ if (!cpumask_empty(uv_nmi_cpu_mask))
uv_nmi_cleanup_mask();
atomic_set(&uv_nmi_cpus_in_nmi, -1);
atomic_set(&uv_nmi_cpu, -1);
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
index 05f3d7876e44..95a0c57ab5bb 100644
--- a/drivers/cpufreq/qcom-cpufreq-hw.c
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -482,7 +482,7 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
}

qcom_get_related_cpus(index, policy->cpus);
- if (!cpumask_weight(policy->cpus)) {
+ if (cpumask_empty(policy->cpus)) {
dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
ret = -ENOENT;
goto error;
diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 1e0cd4d165f0..919fa6e3f462 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -154,7 +154,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
* table and opp-shared.
*/
ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
- if (ret || !cpumask_weight(priv->opp_shared_cpus)) {
+ if (ret || cpumask_empty(priv->opp_shared_cpus)) {
/*
* Either opp-table is not set or no opp-shared was found.
* Use the CPU mask from SCMI to designate CPUs sharing an OPP
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 0b488d49694c..962e8d6bf6ea 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -1048,7 +1048,7 @@ static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
GEM_BUG_ON(!pmu->base.event_init);

/* Select the first online CPU as a designated reader. */
- if (!cpumask_weight(&i915_pmu_cpumask))
+ if (cpumask_empty(&i915_pmu_cpumask))
cpumask_set_cpu(cpu, &i915_pmu_cpumask);

return 0;
diff --git a/drivers/infiniband/hw/hfi1/affinity.c b/drivers/infiniband/hw/hfi1/affinity.c
index 98c813ba4304..38eee675369a 100644
--- a/drivers/infiniband/hw/hfi1/affinity.c
+++ b/drivers/infiniband/hw/hfi1/affinity.c
@@ -667,7 +667,7 @@ int hfi1_dev_affinity_init(struct hfi1_devdata *dd)
* engines, use the same CPU cores as general/control
* context.
*/
- if (cpumask_weight(&entry->def_intr.mask) == 0)
+ if (cpumask_empty(&entry->def_intr.mask))
cpumask_copy(&entry->def_intr.mask,
&entry->general_intr_mask);
}
@@ -687,7 +687,7 @@ int hfi1_dev_affinity_init(struct hfi1_devdata *dd)
* vectors, use the same CPU core as the general/control
* context.
*/
- if (cpumask_weight(&entry->comp_vect_mask) == 0)
+ if (cpumask_empty(&entry->comp_vect_mask))
cpumask_copy(&entry->comp_vect_mask,
&entry->general_intr_mask);
}
diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c
index fd079215c17f..142a7431745f 100644
--- a/drivers/irqchip/irq-bcm6345-l1.c
+++ b/drivers/irqchip/irq-bcm6345-l1.c
@@ -315,7 +315,7 @@ static int __init bcm6345_l1_of_init(struct device_node *dn,
cpumask_set_cpu(idx, &intc->cpumask);
}

- if (!cpumask_weight(&intc->cpumask)) {
+ if (cpumask_empty(&intc->cpumask)) {
ret = -ENODEV;
goto out_free;
}
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index f7ff8919dc9b..18740faf0eb1 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -258,7 +258,7 @@ static int __irq_build_affinity_masks(unsigned int startvec,
nodemask_t nodemsk = NODE_MASK_NONE;
struct node_vectors *node_vectors;

- if (!cpumask_weight(cpu_mask))
+ if (cpumask_empty(cpu_mask))
return 0;

nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
diff --git a/kernel/padata.c b/kernel/padata.c
index 18d3a5c699d8..e5819bb8bd1d 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -181,7 +181,7 @@ int padata_do_parallel(struct padata_shell *ps,
goto out;

if (!cpumask_test_cpu(*cb_cpu, pd->cpumask.cbcpu)) {
- if (!cpumask_weight(pd->cpumask.cbcpu))
+ if (cpumask_empty(pd->cpumask.cbcpu))
goto out;

/* Select an alternate fallback CPU and notify the caller. */
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 1e40519d1a05..bc038a451768 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -1169,7 +1169,7 @@ void __init rcu_init_nohz(void)
struct rcu_data *rdp;

#if defined(CONFIG_NO_HZ_FULL)
- if (tick_nohz_full_running && cpumask_weight(tick_nohz_full_mask))
+ if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask))
need_rcu_nocb_mask = true;
#endif /* #if defined(CONFIG_NO_HZ_FULL) */

@@ -1353,7 +1353,7 @@ static void __init rcu_organize_nocb_kthreads(void)
*/
void rcu_bind_current_to_nocb(void)
{
- if (cpumask_available(rcu_nocb_mask) && cpumask_weight(rcu_nocb_mask))
+ if (cpumask_available(rcu_nocb_mask) && !cpumask_empty(rcu_nocb_mask))
WARN_ON(sched_setaffinity(current->pid, rcu_nocb_mask));
}
EXPORT_SYMBOL_GPL(rcu_bind_current_to_nocb);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 54ef0e8c8742..3857ff6cb6f7 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1216,7 +1216,7 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
cpu != outgoingcpu)
cpumask_set_cpu(cpu, cm);
cpumask_and(cm, cm, housekeeping_cpumask(HK_FLAG_RCU));
- if (cpumask_weight(cm) == 0)
+ if (cpumask_empty(cm))
cpumask_copy(cm, housekeeping_cpumask(HK_FLAG_RCU));
set_cpus_allowed_ptr(t, cm);
mutex_unlock(&rnp->boost_kthread_mutex);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 83872f95a1ea..9b3ec14227e1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8715,7 +8715,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
{
int ret = 1;

- if (!cpumask_weight(cur))
+ if (cpumask_empty(cur))
return ret;

ret = dl_cpuset_cpumask_can_shrink(cur, trial);
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index d201a7052a29..8478e2a8cd65 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -74,7 +74,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
break;
}

- if (!cpumask_weight(sched_group_span(group))) {
+ if (cpumask_empty(sched_group_span(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: empty group\n");
break;
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 95d7ca35bdf2..cee5da1e54c4 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -343,7 +343,7 @@ void clocksource_verify_percpu(struct clocksource *cs)
cpus_read_lock();
preempt_disable();
clocksource_verify_choose_cpus();
- if (cpumask_weight(&cpus_chosen) == 0) {
+ if (cpumask_empty(&cpus_chosen)) {
preempt_enable();
cpus_read_unlock();
pr_warn("Not enough CPUs to check clocksource '%s'.\n", cs->name);
diff --git a/mm/vmstat.c b/mm/vmstat.c
index d701c335628c..295642e2c24c 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -2032,7 +2032,7 @@ static void __init init_cpu_node_state(void)
int node;

for_each_online_node(node) {
- if (cpumask_weight(cpumask_of_node(node)) > 0)
+ if (!cpumask_empty(cpumask_of_node(node)))
node_set_state(node, N_CPU);
}
}
@@ -2059,7 +2059,7 @@ static int vmstat_cpu_dead(unsigned int cpu)

refresh_zone_stat_thresholds();
node_cpus = cpumask_of_node(node);
- if (cpumask_weight(node_cpus) > 0)
+ if (!cpumask_empty(node_cpus))
return 0;

node_clear_state(node, N_CPU);