cpumask: Introduce for_each_cpu_andnot()

for_each_cpu_and() is very convenient as it saves having to allocate a
temporary cpumask to store the result of cpumask_and(). The same issue
applies to cpumask_andnot() which doesn't actually need temporary storage
for iteration purposes.

Following what has been done for for_each_cpu_and(), introduce
for_each_cpu_andnot().

Signed-off-by: Valentin Schneider <vschneid@redhat.com>

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 286804bfe3b722f7adfd7bbe55ea4606baa52c92..2f065ad97541f84b44c8581cd32fc9b4969f5773 100644 (file)
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -306,6 +306,24 @@ unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int sta
 #define for_each_cpu_and(cpu, mask1, mask2)                            \
        for_each_and_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), nr_cpumask_bits)
 
+/**
+ * for_each_cpu_andnot - iterate over every cpu present in one mask, excluding
+ *                      those present in another.
+ * @cpu: the (optionally unsigned) integer iterator
+ * @mask1: the first cpumask pointer
+ * @mask2: the second cpumask pointer
+ *
+ * This saves a temporary CPU mask in many places.  It is equivalent to:
+ *     struct cpumask tmp;
+ *     cpumask_andnot(&tmp, &mask1, &mask2);
+ *     for_each_cpu(cpu, &tmp)
+ *             ...
+ *
+ * After the loop, cpu is >= nr_cpu_ids.
+ */
+#define for_each_cpu_andnot(cpu, mask1, mask2)                         \
+       for_each_andnot_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), nr_cpumask_bits)
+
 /**
  * cpumask_any_but - return a "random" in a cpumask, but not this one.
  * @mask: the cpumask to search

diff --git a/include/linux/find.h b/include/linux/find.h
index 2235af19e7e1b110dc2eefc035b92f63f0a15446..ccaf61a0f5fd5a6c89d7507fece5ea3afff56116 100644 (file)
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -498,6 +498,11 @@ unsigned long find_next_bit_le(const void *addr, unsigned
             (bit) = find_next_and_bit((addr1), (addr2), (size), (bit)), (bit) < (size);\
             (bit)++)
 
+#define for_each_andnot_bit(bit, addr1, addr2, size) \
+       for ((bit) = 0;                                                                 \
+            (bit) = find_next_andnot_bit((addr1), (addr2), (size), (bit)), (bit) < (size);\
+            (bit)++)
+
 /* 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)), (bit) < (size); (bit)++)