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Date:   Mon,  4 Oct 2021 22:40:52 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Yury Norov <yury.norov@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-perf-users@...r.kernel.org,
        kvm@...r.kernel.org,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Alexander Lobakin <alobakin@...me>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Alexey Klimov <aklimov@...hat.com>,
        Andrea Merello <andrea.merello@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Ben Gardon <bgardon@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Brian Cain <bcain@...eaurora.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Lameter <cl@...ux.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Dennis Zhou <dennis@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Ian Rogers <irogers@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
        Joe Perches <joe@...ches.com>, Jonas Bonn <jonas@...thpole.se>,
        Leo Yan <leo.yan@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Rich Felker <dalias@...c.org>,
        Samuel Mendoza-Jonas <sam@...dozajonas.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Shuah Khan <shuah@...nel.org>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tejun Heo <tj@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Will Deacon <will@...nel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>
Subject: [PATCH 09/16] 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@...il.com>
Tested-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
---
 arch/powerpc/include/asm/cputhreads.h |  2 +-
 block/blk-mq.c                        |  2 +-
 drivers/net/virtio_net.c              |  2 +-
 drivers/soc/fsl/qbman/bman_portal.c   |  2 +-
 drivers/soc/fsl/qbman/qman_portal.c   |  2 +-
 include/linux/cpumask.h               | 16 ++++++++++++++++
 kernel/time/clocksource.c             |  4 ++--
 7 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/cputhreads.h b/arch/powerpc/include/asm/cputhreads.h
index b167186aaee4..44286df21d2a 100644
--- a/arch/powerpc/include/asm/cputhreads.h
+++ b/arch/powerpc/include/asm/cputhreads.h
@@ -52,7 +52,7 @@ static inline cpumask_t cpu_thread_mask_to_cores(const struct cpumask *threads)
 	for (i = 0; i < NR_CPUS; i += threads_per_core) {
 		cpumask_shift_left(&tmp, &threads_core_mask, i);
 		if (cpumask_intersects(threads, &tmp)) {
-			cpu = cpumask_next_and(-1, &tmp, cpu_online_mask);
+			cpu = cpumask_first_and(&tmp, cpu_online_mask);
 			if (cpu < nr_cpu_ids)
 				cpumask_set_cpu(cpu, &res);
 		}
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 108a352051be..d4f5a05f4470 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2536,7 +2536,7 @@ 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 79bd2585ec6b..a3b16790846c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2085,7 +2085,7 @@ 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 c7be6c5b7523..862856fe0056 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)
 {
@@ -201,6 +206,17 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp)
 	return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
+/**
+ * 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
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);
 	}
-- 
2.30.2

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