cpumask: replace cpumask_next_* with cpumask_first_* where appropriate

cpumask_first() is a more effective analogue of 'next' version if n == -1
(which means start == 0). This patch replaces 'next' with 'first' where
things look trivial.

There's no cpumask_first_zero() function, so create it.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

6 files changed, 22 insertions, 6 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8874a63ae952..ef56e753ab38 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2967,7 +2967,7 @@ static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
 static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
 		struct blk_mq_hw_ctx *hctx)
 {
-	if (cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) != cpu)
+	if (cpumask_first_and(hctx->cpumask, cpu_online_mask) != cpu)
 		return false;
 	if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
 		return false;
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b107835242ad..8c70ab3c436a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2101,7 +2101,7 @@ static void virtnet_set_affinity(struct virtnet_info *vi)
 	stragglers = num_cpu >= vi->curr_queue_pairs ?
 			num_cpu % vi->curr_queue_pairs :
 			0;
-	cpu = cpumask_next(-1, cpu_online_mask);
+	cpu = cpumask_first(cpu_online_mask);
 
 	for (i = 0; i < vi->curr_queue_pairs; i++) {
 		group_size = stride + (i < stragglers ? 1 : 0);
diff --git a/drivers/soc/fsl/qbman/bman_portal.c b/drivers/soc/fsl/qbman/bman_portal.c
index acda8a5637c5..4d7b9caee1c4 100644
--- a/drivers/soc/fsl/qbman/bman_portal.c
+++ b/drivers/soc/fsl/qbman/bman_portal.c
@@ -155,7 +155,7 @@ static int bman_portal_probe(struct platform_device *pdev)
 	}
 
 	spin_lock(&bman_lock);
-	cpu = cpumask_next_zero(-1, &portal_cpus);
+	cpu = cpumask_first_zero(&portal_cpus);
 	if (cpu >= nr_cpu_ids) {
 		__bman_portals_probed = 1;
 		/* unassigned portal, skip init */
diff --git a/drivers/soc/fsl/qbman/qman_portal.c b/drivers/soc/fsl/qbman/qman_portal.c
index 96f74a1dc603..e23b60618c1a 100644
--- a/drivers/soc/fsl/qbman/qman_portal.c
+++ b/drivers/soc/fsl/qbman/qman_portal.c
@@ -248,7 +248,7 @@ static int qman_portal_probe(struct platform_device *pdev)
 	pcfg->pools = qm_get_pools_sdqcr();
 
 	spin_lock(&qman_lock);
-	cpu = cpumask_next_zero(-1, &portal_cpus);
+	cpu = cpumask_first_zero(&portal_cpus);
 	if (cpu >= nr_cpu_ids) {
 		__qman_portals_probed = 1;
 		/* unassigned portal, skip init */
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index c4e1b9ea0ba4..64dae70d31f5 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -123,6 +123,11 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp)
 	return 0;
 }
 
+static inline unsigned int cpumask_first_zero(const struct cpumask *srcp)
+{
+	return 0;
+}
+
 static inline unsigned int cpumask_first_and(const struct cpumask *srcp1,
 					     const struct cpumask *srcp2)
 {
@@ -202,6 +207,17 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp)
 }
 
 /**
+ * cpumask_first_zero - get the first unset cpu in a cpumask
+ * @srcp: the cpumask pointer
+ *
+ * Returns >= nr_cpu_ids if all cpus are set.
+ */
+static inline unsigned int cpumask_first_zero(const struct cpumask *srcp)
+{
+	return find_first_zero_bit(cpumask_bits(srcp), nr_cpumask_bits);
+}
+
+/**
  * cpumask_first_and - return the first cpu from *srcp1 & *srcp2
  * @src1p: the first input
  * @src2p: the second input
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index b8a14d2fb5ba..f29d1a524fa5 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -257,7 +257,7 @@ static void clocksource_verify_choose_cpus(void)
 		return;
 
 	/* Make sure to select at least one CPU other than the current CPU. */
-	cpu = cpumask_next(-1, cpu_online_mask);
+	cpu = cpumask_first(cpu_online_mask);
 	if (cpu == smp_processor_id())
 		cpu = cpumask_next(cpu, cpu_online_mask);
 	if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
@@ -279,7 +279,7 @@ static void clocksource_verify_choose_cpus(void)
 		cpu = prandom_u32() % nr_cpu_ids;
 		cpu = cpumask_next(cpu - 1, cpu_online_mask);
 		if (cpu >= nr_cpu_ids)
-			cpu = cpumask_next(-1, cpu_online_mask);
+			cpu = cpumask_first(cpu_online_mask);
 		if (!WARN_ON_ONCE(cpu >= nr_cpu_ids))
 			cpumask_set_cpu(cpu, &cpus_chosen);
 	}