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'
[-Werror,-Wpointer-bool-conversion]

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

Link: http://lkml.kernel.org/r/20170412182030.83657-1-mka@chromium.org
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Grant Grundler <grundler@chromium.org>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Michael Davidson <md@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions