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-rw-r--r--lib/llist.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/lib/llist.c b/lib/llist.c
index 6e668fa5a2..f21d0cfbba 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -66,6 +66,34 @@ struct llist_node *llist_del_first(struct llist_head *head)
EXPORT_SYMBOL_GPL(llist_del_first);
/**
+ * llist_del_first_this - delete given entry of lock-less list if it is first
+ * @head: the head for your lock-less list
+ * @this: a list entry.
+ *
+ * If head of the list is given entry, delete and return %true else
+ * return %false.
+ *
+ * Multiple callers can safely call this concurrently with multiple
+ * llist_add() callers, providing all the callers offer a different @this.
+ */
+bool llist_del_first_this(struct llist_head *head,
+ struct llist_node *this)
+{
+ struct llist_node *entry, *next;
+
+ /* acquire ensures orderig wrt try_cmpxchg() is llist_del_first() */
+ entry = smp_load_acquire(&head->first);
+ do {
+ if (entry != this)
+ return false;
+ next = READ_ONCE(entry->next);
+ } while (!try_cmpxchg(&head->first, &entry, next));
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(llist_del_first_this);
+
+/**
* llist_reverse_order - reverse order of a llist chain
* @head: first item of the list to be reversed
*