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Date: Wed, 6 Aug 2008 13:26:19 -0700 From: "Luis R. Rodriguez" <lrodriguez@...eros.com> To: Peter Zijlstra <peterz@...radead.org> CC: Luis Rodriguez <Luis.Rodriguez@...eros.com>, "linville@...driver.com" <linville@...driver.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>, "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>, "ath9k-devel@...ts.ath9k.org" <ath9k-devel@...ts.ath9k.org> Subject: Re: [PATCH 1/4] list.h: Add list_splice_tail() and list_splice_tail_init() On Tue, Aug 05, 2008 at 02:03:15AM -0700, Peter Zijlstra wrote: > On Mon, 2008-08-04 at 15:48 -0700, Luis R. Rodriguez wrote: > > 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() > > In the -rt tree we have this: > > --- > rt: list_splice2 > > Introduce list_splice2{,_tail}() which will splice a sub-list denoted > by two list items instead of the full list. > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> I like your version of list_splice_tail() and list_splice_tail_init() more as you re-use __list_splice() and fix it for its use instad of adding a new __list_splice_tail(). You also caught some users of __list_splice() for tail purposes. Its a good thing both versions are functionally equivalent :) otherwise one of us was doing something wrong. We just need to also clarify list_splice() is for stacks and not queues, I can add that. You patch however fails with checkpatch and forgot to add kdoc. I'll correct it. Last, list_splice2() should go in a separate patch and could use just a little bit more documentation as exactly what it does. Also the last hunk doesn't apply as 2.6.27 doesn't have lib/lock_list.c yet. To get ath9k in 2.6.27 we need list_splice_tail() and list_splice_tail_init(), how's this for 2.6.27: -- 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@...llo.nl> Signed-off-by: Luis R. Rodriguez <lrodriguez@...eros.com> --- drivers/dma/ioat_dma.c | 2 +- drivers/usb/host/ehci-q.c | 2 +- include/linux/list.h | 39 ++++++++++++++++++++++++++++++--------- 3 files changed, 32 insertions(+), 11 deletions(-) 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 @@ 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 2622b65..3712b92 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 453916b..61034a6 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 +263,16 @@ 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); + } +} + +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); } } -- 1.5.6.rc2.15.g457bb.dirty -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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