linux-kernel - [PATCH v3 1/9] cpumask: Make cpumask_full() check for nr_cpu

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Date:   Thu, 25 Aug 2022 19:12:02 +0100
From:   Valentin Schneider <vschneid@...hat.com>
To:     netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mel Gorman <mgorman@...e.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Gal Pressman <gal@...dia.com>,
        Tariq Toukan <tariqt@...dia.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>
Subject: [PATCH v3 1/9] cpumask: Make cpumask_full() check for nr_cpu_ids bits

Consider a system with 4 CPUs and:
  CONFIG_NR_CPUS=64
  CONFIG_CPUMASK_OFFSTACK=n

In this situation, we have:
  nr_cpumask_bits == NR_CPUS == 64
  nr_cpu_ids = 4

Per smp.c::setup_nr_cpu_ids(), nr_cpu_ids <= NR_CPUS, so we want
cpumask_full() to check for nr_cpu_ids bits set.

This issue is currently pointed out by the cpumask KUnit tests:

  [   14.072028]     # test_cpumask_weight: EXPECTATION FAILED at lib/test_cpumask.c:57
  [   14.072028]     Expected cpumask_full(((const struct cpumask *)&__cpu_possible_mask)) to be true, but is false
  [   14.079333]     not ok 1 - test_cpumask_weight

Signed-off-by: Valentin Schneider <vschneid@...hat.com>
---
 include/linux/cpumask.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index bd047864c7ac..1414ce8cd003 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -574,7 +574,7 @@ static inline bool cpumask_empty(const struct cpumask *srcp)
  */
 static inline bool cpumask_full(const struct cpumask *srcp)
 {
-	return bitmap_full(cpumask_bits(srcp), nr_cpumask_bits);
+	return bitmap_full(cpumask_bits(srcp), nr_cpu_ids);
 }
 
 /**
-- 
2.31.1