On Tue, Jan 07, 2025 at 02:28:31PM +0100, Alexander Gordeev wrote:

On Sat, Dec 28, 2024 at 10:49:38AM -0800, Yury Norov wrote:

Hi Yury,

quoted

cpumask_next_wrap_old() has two additional parameters, comparing to it's
analogue in linux/find.h find_next_bit_wrap(). The reason for that is
historical.

Before 4fe49b3b97c262 ("lib/bitmap: introduce for_each_set_bit_wrap()
macro"), cpumask_next_wrap() was used to implement for_each_cpu_wrap()
iterator. Now that the iterator is an alias to generic
for_each_set_bit_wrap(), the additional parameters aren't used and may
confuse readers.

All existing users call cpumask_next_wrap() in a way that makes it
possible to turn it to straight and simple alias to find_next_bit_wrap().

In a couple places kernel users opencode missing cpumask_next_and_wrap().
Add it as well.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/cpumask.h | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index b267a4f6a917..18c9908d50c4 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h

@@ -284,6 +284,43 @@ unsigned int cpumask_next_and(int n, const struct cpumask *src1p,
 		small_cpumask_bits, n + 1);
 }
 
+/**
+ * cpumask_next_and_wrap - get the next cpu in *src1p & *src2p, starting from
+ *			   @n and wrapping around, if needed
+ * @n: the cpu prior to the place to search (i.e. return will be > @n)
+ * @src1p: the first cpumask pointer
+ * @src2p: the second cpumask pointer
+ *
+ * Return: >= nr_cpu_ids if no further cpus set in both.
+ */
+static __always_inline
+unsigned int cpumask_next_and_wrap(int n, const struct cpumask *src1p,
+			      const struct cpumask *src2p)
+{
+	/* -1 is a legal arg here. */
+	if (n != -1)
+		cpumask_check(n);
+	return find_next_and_bit_wrap(cpumask_bits(src1p), cpumask_bits(src2p),
+		small_cpumask_bits, n + 1);
+}
+
+/*
+ * cpumask_next_wrap - get the next cpu in *src, starting from
+ *			   @n and wrapping around, if needed

Does it mean the search wraps a cpumask and starts from the beginning
if the bit is not found and returns >= nr_cpu_ids if @n crosses itself?

quoted

+ * @n: the cpu prior to the place to search
+ * @src: cpumask pointer
+ *
+ * Return: >= nr_cpu_ids if no further cpus set in both.

It looks like Return is a cpumask_next_and_wrap() comment leftover.

quoted

+ */
+static __always_inline
+unsigned int cpumask_next_wrap(int n, const struct cpumask *src)
+{
+	/* -1 is a legal arg here. */
+	if (n != -1)
+		cpumask_check(n);
+	return find_next_bit_wrap(cpumask_bits(src), small_cpumask_bits, n + 1);
+}
+
 /**
  * for_each_cpu - iterate over every cpu in a mask
  * @cpu: the (optionally unsigned) integer iterator

Thanks!

Thanks, I'll update the comments.