[tip: sched/core] <linux/list.h>: Introduce the list_for_each_reverse() method

[tip-bot2 for Ingo Molnar]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     8bf0cdfac7f8aa3fa6151b5c5f5eebdb44a64e89
Gitweb:        https://git.kernel.org/tip/8bf0cdfac7f8aa3fa6151b5c5f5eebdb44a64e89
Author:        Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate:    Thu, 21 Sep 2023 11:32:58 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 22 Sep 2023 09:38:42 +02:00

<linux/list.h>: Introduce the list_for_each_reverse() method

The list_head counterpart of list_for_each_entry_reverse() was missing,
add it to complete the list handling APIs in <linux/list.h>.

[ This new API is also relied on by a WIP scheduler patch, so this
  variant is not a theoretical possibility only. ]

Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 include/linux/list.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/list.h b/include/linux/list.h
index 164b4d0..1837cae 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -687,6 +687,14 @@ static inline void list_splice_tail_init(struct list_head *list,
 	for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
 
 /**
+ * list_for_each_reverse - iterate backwards over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_reverse(pos, head) \
+	for (pos = (head)->prev; pos != (head); pos = pos->prev)
+
+/**
  * list_for_each_rcu - Iterate over a list in an RCU-safe fashion
  * @pos:	the &struct list_head to use as a loop cursor.
  * @head:	the head for your list.