linux-kernel - [PATCH 2/2] cpumask: make whole cpumask operations like copy to work with NR

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Date:	Thu, 26 Feb 2015 01:19:11 -0500
From:	green@...uxhacker.ru
To:	Rusty Russell <rusty@...tcorp.com.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>
Cc:	linux-kernel@...r.kernel.org, Oleg Drokin <green@...uxhacker.ru>
Subject: [PATCH 2/2] cpumask: make whole cpumask operations like copy to work with NR_CPUS bits

From: Oleg Drokin <green@...uxhacker.ru>

When we are doing things like cpumask_copy, and CONFIG_CPUMASK_OFFSTACK
is set, we only copy actual number of bits equal to number of CPUs
we have. But underlying allocations got NR_CPUS = 8192, so
if the cpumask is allocated on the stack or has other prefilled values
there's a lot of garbage left that might become exposed as more CPUs are
added into the system.
The patch converts such whole-mask functions:
cpumask_setall, cpumask_clear, cpumask_copy
to operate on the whole NR_CPUS value.

Signed-off-by: Oleg Drokin <green@...uxhacker.ru>
---
 include/linux/cpumask.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index f0599e1..28a8bb3 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -324,21 +324,21 @@ static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask)
 }
 
 /**
- * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask
+ * cpumask_setall - set all cpus (< NR_CPUS) in a cpumask
  * @dstp: the cpumask pointer
  */
 static inline void cpumask_setall(struct cpumask *dstp)
 {
-	bitmap_fill(cpumask_bits(dstp), nr_cpumask_bits);
+	bitmap_fill(cpumask_bits(dstp), NR_CPUS);
 }
 
 /**
- * cpumask_clear - clear all cpus (< nr_cpu_ids) in a cpumask
+ * cpumask_clear - clear all cpus (< NR_CPUS) in a cpumask
  * @dstp: the cpumask pointer
  */
 static inline void cpumask_clear(struct cpumask *dstp)
 {
-	bitmap_zero(cpumask_bits(dstp), nr_cpumask_bits);
+	bitmap_zero(cpumask_bits(dstp), NR_CPUS);
 }
 
 /**
@@ -470,7 +470,7 @@ static inline bool cpumask_full(const struct cpumask *srcp)
 
 /**
  * cpumask_weight - Count of bits in *srcp
- * @srcp: the cpumask to count bits (< nr_cpu_ids) in.
+ * @srcp: the cpumask to count bits (< NR_CPUS) in.
  */
 static inline unsigned int cpumask_weight(const struct cpumask *srcp)
 {
@@ -511,7 +511,7 @@ static inline void cpumask_shift_left(struct cpumask *dstp,
 static inline void cpumask_copy(struct cpumask *dstp,
 				const struct cpumask *srcp)
 {
-	bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
+	bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), NR_CPUS);
 }
 
 /**
-- 
2.1.0

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