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From:   Valentin Schneider <vschneid@redhat.com>
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Subject: [PATCH v3 1/9] cpumask: Make cpumask_full() check for nr_cpu_ids bits
Date:   Thu, 25 Aug 2022 19:12:02 +0100
Message-Id: <20220825181210.284283-2-vschneid@redhat.com>
In-Reply-To: <20220825181210.284283-1-vschneid@redhat.com>
References: <20220825181210.284283-1-vschneid@redhat.com>
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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@redhat.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