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SubjectRe: [PATCH 08/13] list: add a new LRU list type
On Tue, Aug 23, 2011 at 06:56:21PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Several subsystems use the same construct for LRU lists - a list
> head, a spin lock and and item count. They also use exactly the same
> code for adding and removing items from the LRU. Create a generic
> type for these LRU lists.
>
> This is the beginning of generic, node aware LRUs for shrinkers to
> work with.

Why list_lru vs the more natural sounding lru_list?

> diff --git a/lib/Makefile b/lib/Makefile
> index d5d175c..a08212f 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -12,7 +12,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
> idr.o int_sqrt.o extable.o prio_tree.o \
> sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
> proportions.o prio_heap.o ratelimit.o show_mem.o \
> - is_single_threaded.o plist.o decompress.o find_next_bit.o
> + is_single_threaded.o plist.o decompress.o find_next_bit.o \
> + list_lru.o

Di we finally fix the issues with lib-y objects beeing discarded despite
modules relying on the exports?

> +int
> +list_lru_add(
> + struct list_lru *lru,
> + struct list_head *item)
> +{

What about some kerneldoc comments for the helpers?

> + ret = isolate(item, &lru->lock, cb_arg);
> + switch (ret) {
> + case 0: /* item removed from list */
> + lru->nr_items--;
> + removed++;
> + break;
> + case 1: /* item referenced, give another pass */
> + list_move_tail(item, &lru->list);
> + break;
> + case 2: /* item cannot be locked, skip */
> + break;
> + case 3: /* item not freeable, lock dropped */
> + goto restart;

I think the isolate callback returns shoud have symbolic names, i.e.
and enum lru_isolate or similar.

> +int
> +list_lru_init(
> + struct list_lru *lru)
> +{
> + spin_lock_init(&lru->lock);
> + INIT_LIST_HEAD(&lru->list);
> + lru->nr_items = 0;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(list_lru_init);

This one doesn't need a return value.



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