# HG changeset patch
# User yamahata@xxxxxxxxxxxxx
# Date 1185948239 -32400
# Node ID d2884d84d3fd5c52a6699eb7b98ffaf3b8f7a422
# Parent  7b88b56c310b11abe510cf32fc5095bc98979168
[linux, xencomm] 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 <yamahata@xxxxxxxxxxxxx>

diff -r 7b88b56c310b -r d2884d84d3fd drivers/xen/core/xencomm.c
--- a/drivers/xen/core/xencomm.c	Tue Aug 07 16:54:04 2007 +0900
+++ b/drivers/xen/core/xencomm.c	Wed Aug 01 15:03:59 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 failure\n", "xencomm_alloc");
 		return -ENOMEM;