linux-kernel - [PATCH 3/7] cpumask: switch for_each_cpu{,_not} to use for_each

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Date:   Mon, 19 Sep 2022 14:05:55 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Yury Norov <yury.norov@...il.com>
Subject: [PATCH 3/7] cpumask: switch for_each_cpu{,_not} to use for_each_bit()

The difference between for_each_cpu() and for_each_set_bit()
is that the latter uses cpumask_next() instead of find_next_bit(),
and so calls cpumask_check().

This check is useless because the iterator value is not provided by
user. It generates false-positives for the very last iteration
of for_each_cpu().

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 include/linux/cpumask.h | 12 +++---------
 include/linux/find.h    |  5 +++++
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index a1cd4eb1a3d6..3a9566f1373a 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -243,9 +243,7 @@ unsigned int cpumask_next_and(int n, const struct cpumask *src1p,
  * After the loop, cpu is >= nr_cpu_ids.
  */
 #define for_each_cpu(cpu, mask)				\
-	for ((cpu) = -1;				\
-		(cpu) = cpumask_next((cpu), (mask)),	\
-		(cpu) < nr_cpu_ids;)
+	for_each_set_bit(cpu, cpumask_bits(mask), nr_cpumask_bits)
 
 /**
  * for_each_cpu_not - iterate over every cpu in a complemented mask
@@ -255,9 +253,7 @@ unsigned int cpumask_next_and(int n, const struct cpumask *src1p,
  * After the loop, cpu is >= nr_cpu_ids.
  */
 #define for_each_cpu_not(cpu, mask)				\
-	for ((cpu) = -1;					\
-		(cpu) = cpumask_next_zero((cpu), (mask)),	\
-		(cpu) < nr_cpu_ids;)
+	for_each_clear_bit(cpu, cpumask_bits(mask), nr_cpumask_bits)
 
 #if NR_CPUS == 1
 static inline
@@ -310,9 +306,7 @@ unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int sta
  * After the loop, cpu is >= nr_cpu_ids.
  */
 #define for_each_cpu_and(cpu, mask1, mask2)				\
-	for ((cpu) = -1;						\
-		(cpu) = cpumask_next_and((cpu), (mask1), (mask2)),	\
-		(cpu) < nr_cpu_ids;)
+	for_each_and_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), nr_cpumask_bits)
 
 /**
  * cpumask_any_but - return a "random" in a cpumask, but not this one.
diff --git a/include/linux/find.h b/include/linux/find.h
index b100944daba0..128615a3f93e 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -390,6 +390,11 @@ unsigned long find_next_bit_le(const void *addr, unsigned
 	     (bit) < (size);					\
 	     (bit) = find_next_bit((addr), (size), (bit) + 1))
 
+#define for_each_and_bit(bit, addr1, addr2, size) \
+	for ((bit) = find_next_and_bit((addr1), (addr2), (size), 0);		\
+	     (bit) < (size);							\
+	     (bit) = find_next_and_bit((addr1), (addr2), (size), (bit) + 1))
+
 /* same as for_each_set_bit() but use bit as value to start with */
 #define for_each_set_bit_from(bit, addr, size) \
 	for ((bit) = find_next_bit((addr), (size), (bit));	\
-- 
2.34.1