Commit 4aec74bc authored by Yury Norov's avatar Yury Norov
Browse files

arch/x86: replace cpumask_weight with cpumask_empty where appropriate 



In some cases, arch/x86 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: default avatarYury Norov <yury.norov@gmail.com>
Reviewed-by: default avatarSteve Wahl <steve.wahl@hpe.com>
parent b6dad11d

arch/x86/kernel/cpu/resctrl/rdtgroup.c

+7 −7
Original line number Diff line number Diff line
@@ -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;

arch/x86/mm/mmio-mod.c

+1 −1
Original line number Diff line number Diff line
@@ -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) {

arch/x86/platform/uv/uv_nmi.c

+1 −1
Original line number Diff line number Diff line
@@ -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);