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Subject[PATCH v3 2/6] list_bl: Add hlist_bl_add_before/behind helpers
Date
Add hlist_bl_add_before/behind helpers to add an element before/after an
existing element in a bl_list.

Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
---
include/linux/list_bl.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
index 3fc2cc57ba1b..ae1b541446c9 100644
--- a/include/linux/list_bl.h
+++ b/include/linux/list_bl.h
@@ -86,6 +86,32 @@ static inline void hlist_bl_add_head(struct hlist_bl_node *n,
hlist_bl_set_first(h, n);
}

+static inline void hlist_bl_add_before(struct hlist_bl_node *n,
+ struct hlist_bl_node *next)
+{
+ struct hlist_bl_node **pprev = next->pprev;
+
+ n->pprev = pprev;
+ n->next = next;
+ next->pprev = &n->next;
+
+ /* pprev may be `first`, so be careful not to lose the lock bit */
+ WRITE_ONCE(*pprev,
+ (struct hlist_bl_node *)
+ ((uintptr_t)n | ((uintptr_t)*pprev & LIST_BL_LOCKMASK)));
+}
+
+static inline void hlist_bl_add_behind(struct hlist_bl_node *n,
+ struct hlist_bl_node *prev)
+{
+ n->next = prev->next;
+ n->pprev = &prev->next;
+ prev->next = n;
+
+ if (n->next)
+ n->next->pprev = &n->next;
+}
+
static inline void __hlist_bl_del(struct hlist_bl_node *n)
{
struct hlist_bl_node *next = n->next;
--
2.11.0
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