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Subject[PATCH v2 1/2] cpumask: Add helper cpumask_available()
With CONFIG_CPUMASK_OFFSTACK=y cpumask_var_t is a struct cpumask
pointer, otherwise a struct cpumask array with a single element.

Some code dealing with cpumasks needs to validate that a cpumask_var_t
is not a NULL pointer when CONFIG_CPUMASK_OFFSTACK=y. This is typically
done by performing the check always, regardless of the underlying type
of cpumask_var_t. This works in both cases, however clang raises a
warning like this when CONFIG_CPUMASK_OFFSTACK=n:

kernel/irq/manage.c:839:28: error: address of array
'desc->irq_common_data.affinity' will always evaluate to 'true'

Add the inline helper cpumask_available() which only performs the
pointer check if CONFIG_CPUMASK_OFFSTACK=y.

Signed-off-by: Matthias Kaehlcke <>
Changes in v2:
- Patch added

include/linux/cpumask.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 96f1e88b767c..1a675604b17d 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -667,6 +667,11 @@ void alloc_bootmem_cpumask_var(cpumask_var_t *mask);
void free_cpumask_var(cpumask_var_t mask);
void free_bootmem_cpumask_var(cpumask_var_t mask);

+static inline bool cpumask_available(cpumask_var_t mask)
+ return mask != NULL;
typedef struct cpumask cpumask_var_t[1];

@@ -708,6 +713,11 @@ static inline void free_cpumask_var(cpumask_var_t mask)
static inline void free_bootmem_cpumask_var(cpumask_var_t mask)
+static inline bool cpumask_available(cpumask_var_t mask)
+ return true;

/* It's common to want to use cpu_all_mask in struct member initializers,
 \ /
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