xencomm take 4: linux side remove xencomm page size limit

# HG changeset patch
# User yamahatavalinux.co.jp
# Date 1187582891 -32400
# Node ID 603694f91c98a6a4f12dcd729053f9ba38d5fc11
# Parent  b5fdf02c38f4765697196f5fad5d1262f2c157f4
remove xencomm page size limit.
Currently xencomm has page size limit so that a domain with
many memory
(e.g. 100GB~) can't be created.

Now that xencomm of xen side accepts struct xencomm_desc
whose address array
crosses page boundary. Thus it isn't necessary to allocate
single page
not to cross page boundary. We can allocate exact sized
memory.
Note that struct xencomm_desc can't cross page boundary and
slab allocator
returns sizeof(void*) aligned pointer.
Where sizeof(*desc) > sizeof(void*), e.g. 32 bit
environment,
the slab allocator return pointer doesn't gurantee that
struct xencomm_desc doesn't cross page boundary. So we fall
back to
page allocator.
PATCHNAME: remove_xencomm_page_size_limit_common_code

Signed-off-by: Isaku Yamahata <yamahatavalinux.co.jp>

diff -r b5fdf02c38f4 -r 603694f91c98
drivers/xen/core/xencomm.c
--- a/drivers/xen/core/xencomm.c	Thu Aug 16 13:44:51 2007
-0600
+++ b/drivers/xen/core/xencomm.c	Mon Aug 20 13:08:11 2007
+0900
 -68,25
+68,54  static int xencomm_init(struct xencomm_d
 	return 0;
 }
 
-/* XXX use slab allocator */
-static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask)
-{
-	struct xencomm_desc *desc;
-
-	desc = (struct xencomm_desc *)__get_free_page(gfp_mask);
-	if (desc == NULL)
-		return NULL;
-
-	desc->nr_addrs = (PAGE_SIZE - sizeof(struct
xencomm_desc)) /
+static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
+					  void *buffer, unsigned long bytes)
+{
+	struct xencomm_desc *desc;
+	unsigned long buffer_ulong = (unsigned long)buffer;
+	unsigned long start = buffer_ulong & PAGE_MASK;
+	unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
+	unsigned long nr_addrs = (end - start + 1) >>
PAGE_SHIFT;
+	unsigned long size = sizeof(*desc) +
+		sizeof(desc->address[0]) * nr_addrs;
+
+	/*
+	 * slab allocator returns at least sizeof(void*) aligned
pointer.
+	 * When sizeof(*desc) > sizeof(void*), struct
xencomm_desc might
+	 * cross page boundary.
+	 */
+	if (sizeof(*desc) > sizeof(void*)) {
+		unsigned long order = get_order(size);
+		desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
+							       order);
+		if (desc == NULL)
+			return NULL;
+
+		desc->nr_addrs =
+			((PAGE_SIZE << order) - sizeof(struct
xencomm_desc)) /
 			sizeof(*desc->address);
-
+	} else {
+		desc = kmalloc(size, gfp_mask);
+		if (desc == NULL)
+			return NULL;
+
+		desc->nr_addrs = nr_addrs;
+	}
 	return desc;
 }
 
 void xencomm_free(struct xencomm_handle *desc)
 {
-	if (desc && !((ulong)desc &
XENCOMM_INLINE_FLAG))
-		free_page((unsigned long)__va(desc));
+	if (desc && !((ulong)desc &
XENCOMM_INLINE_FLAG)) {
+		struct xencomm_desc *desc__ = (struct
xencomm_desc*)desc;
+		if (sizeof(*desc__) > sizeof(void*)) {
+			unsigned long size = sizeof(*desc__) +
+				sizeof(desc__->address[0]) * desc__->nr_addrs;
+			unsigned long order = get_order(size);
+			free_pages((unsigned long)__va(desc), order);
+		} else
+			kfree(__va(desc));
+	}
 }
 
 static int xencomm_create(void *buffer, unsigned long
bytes, struct xencomm_desc **ret, gfp_t gfp_mask)
 -105,7
+134,7  static int xencomm_create(void *buffer, 
 
 	BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
 
-	desc = xencomm_alloc(gfp_mask);
+	desc = xencomm_alloc(gfp_mask, buffer, bytes);
 	if (!desc) {
 		printk("%s failuren",
"xencomm_alloc");
 		return -ENOMEM;

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