From 7d283aee50351ec19eaf654a8690d77c4e1dff50 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Wed, 6 Aug 2008 15:21:26 -0700 Subject: [PATCH] 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 Signed-off-by: Luis R. Rodriguez Signed-off-by: John W. Linville --- drivers/dma/ioat_dma.c | 2 +- drivers/usb/host/ehci-q.c | 2 +- include/linux/list.h | 47 +++++++++++++++++++++++++++++++-------- 3 files changed, 40 insertions(+), 11 deletions(-) diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c index a52156e56886..bc8c6e3470ca 100644 --- a/drivers/dma/ioat_dma.c +++ b/drivers/dma/ioat_dma.c @@ -551,7 +551,7 @@ static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx) /* 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 2622b6596d7c..3712b925b315 100644 --- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -932,7 +932,7 @@ static struct ehci_qh *qh_append_tds ( 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 453916bc0412..a886f27a1181 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -215,21 +215,21 @@ static inline int list_is_singular(const struct list_head *head) } 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 @@ static inline void list_splice(const struct list_head *list, 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 @@ static inline void list_splice_init(struct list_head *list, 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); } }