[PATCH 04/13] Fix ridr_alloc_layer()

[Nadia . Derbey]

[PATCH 04/13]

This patch only fixes the alloc_layer() portion of ridr.c, to make it use the
per-cpu pool of preloaded ridr layer structures.

Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>

---
 lib/ridr.c |   35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

Index: linux-2.6.25-rc8-mm1/lib/ridr.c
===================================================================
--- linux-2.6.25-rc8-mm1.orig/lib/ridr.c	2008-04-11 17:40:13.000000000 +0200
+++ linux-2.6.25-rc8-mm1/lib/ridr.c	2008-04-11 17:43:44.000000000 +0200
@@ -22,20 +22,35 @@ struct ridr_preget {
 };
 DEFINE_PER_CPU(struct ridr_preget, ridr_pregets) = { 0, };
 
+static inline gfp_t ridr_gfp_mask(struct ridr *idp)
+{
+	return idp->gfp_mask & __GFP_BITS_MASK;
+}
+
 static struct ridr_layer *alloc_layer(struct ridr *idp)
 {
-	struct ridr_layer *p;
-	unsigned long flags;
+	struct ridr_layer *ret = NULL;
+	gfp_t gfp_mask = ridr_gfp_mask(idp);
 
-	spin_lock_irqsave(&idp->lock, flags);
-	p = idp->id_free;
-	if (p) {
-		idp->id_free = p->ary[0];
-		idp->id_free_cnt--;
-		p->ary[0] = NULL;
+	if (!(gfp_mask & __GFP_WAIT)) {
+		struct ridr_preget *ridp;
+
+		/*
+		 * Provided the caller has preloaded here, we will always
+		 * succeed in getting a node here (and never reach
+		 * kmem_cache_alloc)
+		 */
+		ridp = &__get_cpu_var(ridr_pregets);
+		if (ridp->nr) {
+			ret = ridp->layers[ridp->nr - 1];
+			ridp->layers[ridp->nr - 1] = NULL;
+			ridp->nr--;
+		}
 	}
-	spin_unlock_irqrestore(&idp->lock, flags);
-	return(p);
+	if (ret == NULL)
+		ret = kmem_cache_alloc(ridr_layer_cache, gfp_mask);
+
+	return ret;
 }
 
 /* only called when idp->lock is held */

--
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