linux-kernel - [tip:irq/core] cpumask: Add helper cpumask

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Date:   Fri, 14 Apr 2017 10:54:58 -0700
From:   tip-bot for Matthias Kaehlcke <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rusty@...tcorp.com.au, hpa@...or.com, ghackmann@...gle.com,
        tglx@...utronix.de, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, mingo@...nel.org, grundler@...omium.org,
        mka@...omium.org, md@...gle.com
Subject: [tip:irq/core] cpumask: Add helper cpumask_available()

Commit-ID:  f7e30f01a9e221067bb4b579e3cfc25cd2617467
Gitweb:     http://git.kernel.org/tip/f7e30f01a9e221067bb4b579e3cfc25cd2617467
Author:     Matthias Kaehlcke <mka@...omium.org>
AuthorDate: Wed, 12 Apr 2017 11:20:29 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 14 Apr 2017 19:50:47 +0200

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.

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

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

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 96f1e88..1a67560 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;
+}
+
 #else
 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;
+}
 #endif /* CONFIG_CPUMASK_OFFSTACK */
 
 /* It's common to want to use cpu_all_mask in struct member initializers,