From 81cf88dc9c8db10fe5ab4495c917be4933730a2a Mon Sep 17 00:00:00 2001
From: "kaf24@firebug.cl.cam.ac.uk" <kaf24@firebug.cl.cam.ac.uk>
Date: Wed, 17 Aug 2005 16:53:30 +0000
Subject: [PATCH] Fix the skbuff allocator for multi-page buffers. pci-dma.c
 still needs fixing to recognise contiguous multi-page buffers. Signed-off-by:
 Keir Fraser <keir@xensource.com>

---
 linux-2.6-xen-sparse/arch/xen/kernel/skbuff.c | 82 +++++++++++++++----
 1 file changed, 66 insertions(+), 16 deletions(-)

diff --git a/linux-2.6-xen-sparse/arch/xen/kernel/skbuff.c b/linux-2.6-xen-sparse/arch/xen/kernel/skbuff.c
index 90274fd599..a7fe1519f6 100644
--- a/linux-2.6-xen-sparse/arch/xen/kernel/skbuff.c
+++ b/linux-2.6-xen-sparse/arch/xen/kernel/skbuff.c
@@ -5,8 +5,6 @@
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/string.h>
-#include <linux/errno.h>
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
 #include <linux/etherdevice.h>
@@ -14,34 +12,86 @@
 #include <linux/init.h>
 #include <asm/io.h>
 #include <asm/page.h>
-
-EXPORT_SYMBOL(__dev_alloc_skb);
+#include <asm-xen/hypervisor.h>
 
 /* Referenced in netback.c. */
 /*static*/ kmem_cache_t *skbuff_cachep;
 
-/* Size must be cacheline-aligned (alloc_skb uses SKB_DATA_ALIGN). */
-#define XEN_SKB_SIZE \
-    ((PAGE_SIZE - sizeof(struct skb_shared_info)) & ~(SMP_CACHE_BYTES - 1))
+#define MAX_SKBUFF_ORDER 2
+static kmem_cache_t *skbuff_order_cachep[MAX_SKBUFF_ORDER + 1];
 
 struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask)
 {
-    struct sk_buff *skb;
-    skb = alloc_skb_from_cache(skbuff_cachep, length + 16, gfp_mask);
-    if ( likely(skb != NULL) )
-        skb_reserve(skb, 16);
-    return skb;
+	struct sk_buff *skb;
+	int order;
+
+	length = SKB_DATA_ALIGN(length + 16);
+	order = get_order(length + sizeof(struct skb_shared_info));
+	if (order > MAX_SKBUFF_ORDER) {
+		printk(KERN_ALERT "Attempt to allocate order %d skbuff. "
+		       "Increase MAX_SKBUFF_ORDER.\n", order);
+		return NULL;
+	}
+
+	skb = alloc_skb_from_cache(
+		skbuff_order_cachep[order], length, gfp_mask);
+	if (skb != NULL)
+		skb_reserve(skb, 16);
+
+	return skb;
 }
 
 static void skbuff_ctor(void *buf, kmem_cache_t *cachep, unsigned long unused)
 {
-    scrub_pages(buf, 1);
+	int order = 0;
+
+	while (skbuff_order_cachep[order] != cachep)
+		order++;
+
+	if (order != 0)
+		xen_create_contiguous_region((unsigned long)buf, order);
+
+	scrub_pages(buf, 1 << order);
+}
+
+static void skbuff_dtor(void *buf, kmem_cache_t *cachep, unsigned long unused)
+{
+	int order = 0;
+
+	while (skbuff_order_cachep[order] != cachep)
+		order++;
+
+	if (order != 0)
+		xen_destroy_contiguous_region((unsigned long)buf, order);
 }
 
 static int __init skbuff_init(void)
 {
-    skbuff_cachep = kmem_cache_create(
-        "xen-skb", PAGE_SIZE, PAGE_SIZE, 0, skbuff_ctor, NULL);
-    return 0;
+	static char name[MAX_SKBUFF_ORDER + 1][20];
+	unsigned long size;
+	int order;
+
+	for (order = 0; order <= MAX_SKBUFF_ORDER; order++) {
+		size = PAGE_SIZE << order;
+		sprintf(name[order], "xen-skb-%lu", size);
+		skbuff_order_cachep[order] = kmem_cache_create(
+			name[order], size, size, 0, skbuff_ctor, skbuff_dtor);
+	}
+
+	skbuff_cachep = skbuff_order_cachep[0];
+
+	return 0;
 }
 __initcall(skbuff_init);
+
+EXPORT_SYMBOL(__dev_alloc_skb);
+
+/*
+ * Local variables:
+ *  c-file-style: "linux"
+ *  indent-tabs-mode: t
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ *  tab-width: 8
+ * End:
+ */
-- 
2.30.2