diff mbox series

[net-next,v6,01/13] list: Add list_next_entry_circular() and list_prev_entry_circular()

Message ID 20220407223629.21487-2-ricardo.martinez@linux.intel.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series net: wwan: t7xx: PCIe driver for MediaTek M.2 modem | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 18143 this patch: 18143
netdev/cc_maintainers warning 4 maintainers not CCed: matthias.bgg@gmail.com linux-mediatek@lists.infradead.org akpm@linux-foundation.org linux-arm-kernel@lists.infradead.org
netdev/build_clang success Errors and warnings before: 3320 this patch: 3320
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 17376 this patch: 17376
netdev/checkpatch warning CHECK: Macro argument 'member' may be better as '(member)' to avoid precedence issues WARNING: line length of 85 exceeds 80 columns WARNING: line length of 86 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Ricardo Martinez April 7, 2022, 10:36 p.m. UTC 
Add macros to get the next or previous entries and wraparound if
needed. For example, calling list_next_entry_circular() on the last
element should return the first element in the list.

Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/list.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
diff mbox series

Patch

diff --git a/include/linux/list.h b/include/linux/list.h
index d7d2bfa1a365..c36e3b9a651b 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -563,6 +563,19 @@  static inline void list_splice_tail_init(struct list_head *list,
 #define list_next_entry(pos, member) \
 	list_entry((pos)->member.next, typeof(*(pos)), member)
 
+/**
+ * list_next_entry_circular - get the next element in list
+ * @pos:	the type * to cursor.
+ * @head:	the list head to take the element from.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the last element (return the first element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_next_entry_circular(pos, head, member) \
+	(list_is_last(&(pos)->member, head) ? \
+	list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))
+
 /**
  * list_prev_entry - get the prev element in list
  * @pos:	the type * to cursor
@@ -571,6 +584,19 @@  static inline void list_splice_tail_init(struct list_head *list,
 #define list_prev_entry(pos, member) \
 	list_entry((pos)->member.prev, typeof(*(pos)), member)
 
+/**
+ * list_prev_entry_circular - get the prev element in list
+ * @pos:	the type * to cursor.
+ * @head:	the list head to take the element from.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the first element (return the last element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_prev_entry_circular(pos, head, member) \
+	(list_is_first(&(pos)->member, head) ? \
+	list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member))
+
 /**
  * list_for_each	-	iterate over a list
  * @pos:	the &struct list_head to use as a loop cursor.