list.h: Add list_splice_tail() and list_splice_tail_init()
If you are using linked lists for queues list_splice() will not do what
you would expect even if you use the elements passed reversed. We need
to handle these differently. We add list_splice_tail() and
list_splice_tail_init().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index a52156e..bc8c6e3 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -551,7 +551,7 @@
/* write address into NextDescriptor field of last desc in chain */
to_ioat_desc(ioat_chan->used_desc.prev)->hw->next =
first->async_tx.phys;
- __list_splice(&new_chain, ioat_chan->used_desc.prev);
+ list_splice_tail(&new_chain, &ioat_chan->used_desc);
ioat_chan->dmacount += desc_count;
ioat_chan->pending += desc_count;
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 2622b65..3712b92 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -932,7 +932,7 @@
list_del (&qtd->qtd_list);
list_add (&dummy->qtd_list, qtd_list);
- __list_splice (qtd_list, qh->qtd_list.prev);
+ list_splice_tail(qtd_list, &qh->qtd_list);
ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
qh->dummy = qtd;
diff --git a/include/linux/list.h b/include/linux/list.h
index 453916b..a886f27 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -215,21 +215,21 @@
}
static inline void __list_splice(const struct list_head *list,
- struct list_head *head)
+ struct list_head *prev,
+ struct list_head *next)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
- struct list_head *at = head->next;
- first->prev = head;
- head->next = first;
+ first->prev = prev;
+ prev->next = first;
- last->next = at;
- at->prev = last;
+ last->next = next;
+ next->prev = last;
}
/**
- * list_splice - join two lists
+ * list_splice - join two lists, this is designed for stacks
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
@@ -237,7 +237,19 @@
struct list_head *head)
{
if (!list_empty(list))
- __list_splice(list, head);
+ __list_splice(list, head, head->next);
+}
+
+/**
+ * list_splice_tail - join two lists, each list being a queue
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice_tail(struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list))
+ __list_splice(list, head->prev, head);
}
/**
@@ -251,7 +263,24 @@
struct list_head *head)
{
if (!list_empty(list)) {
- __list_splice(list, head);
+ __list_splice(list, head, head->next);
+ INIT_LIST_HEAD(list);
+ }
+}
+
+/**
+ * list_splice_tail_init - join two lists, each list being a queue, and
+ * reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_tail_init(struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list)) {
+ __list_splice(list, head->prev, head);
INIT_LIST_HEAD(list);
}
}