linux-kernel - [tip: x86/cleanups] x86: Replace cpumask_weight() with cpumask

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 10 Apr 2022 20:42:28 -0000
From:   "tip-bot2 for Yury Norov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steve Wahl <steve.wahl@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cleanups] x86: Replace cpumask_weight() with
 cpumask_empty() where appropriate

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     3a5ff1f6dd50f5e1c2aa87491910dd6d275af24b
Gitweb:        https://git.kernel.org/tip/3a5ff1f6dd50f5e1c2aa87491910dd6d275af24b
Author:        Yury Norov <yury.norov@...il.com>
AuthorDate:    Thu, 10 Feb 2022 14:49:00 -08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Sun, 10 Apr 2022 22:35:38 +02:00

x86: Replace cpumask_weight() with cpumask_empty() where appropriate

In some cases, x86 code calls cpumask_weight() to check if any bit of a
given cpumask is set.

This can be done 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@...il.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Steve Wahl <steve.wahl@....com>
Link: https://lore.kernel.org/r/20220210224933.379149-17-yury.norov@gmail.com

---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 14 +++++++-------
 arch/x86/mm/mmio-mod.c                 |  2 +-
 arch/x86/platform/uv/uv_nmi.c          |  2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 83f901e..f276aff 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 933a2eb..c3317f0 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 1e9ff28..ea277fc 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);