On Tue, Aug 23, 2011 at 05:20:56AM -0400, Christoph Hellwig wrote:

On Tue, Aug 23, 2011 at 06:56:21PM +1000, Dave Chinner wrote:

quoted

From: Dave Chinner <redacted>

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?

because the mmzone.h claimed that namespace:

enum lru_list {
        LRU_INACTIVE_ANON = LRU_BASE,
        LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
        LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
        LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
        LRU_UNEVICTABLE,
        NR_LRU_LISTS
};

and it is widely spewed through the mm code. I didn't really feel
like having to clean that mess up first....

quoted

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?

Don't care. The list_lru code is used by the VFs, so it will always
be built in....

quoted

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

What about some kerneldoc comments for the helpers?

Yup, to be done.

quoted

+		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.

Will do.

quoted

+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.

No, not yet. I'll kill it.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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