IO resources: add reserve_region_with_split()

add reserve_region_with_split() to not lose e820 reserved entries if
they overlap with existing IO regions:

with test case by extend 0xe0000000 - 0xeffffff to 0xdd800000 -
we get:
	e0000000-efffffff : PCI MMCONFIG 0
		 e0000000-efffffff : reserved

and in /proc/iomem we get:
	found conflict for reserved [dd800000, efffffff], try to reserve with split
	    __reserve_region_with_split: (PCI Bus #80) [dd000000, ddffffff], res: (reserved) [dd800000, efffffff]
	    __reserve_region_with_split: (PCI Bus #00) [de000000, dfffffff], res: (reserved) [de000000, efffffff]
	initcall pci_subsys_init+0x0/0x121 returned 0 after 381 msecs
in dmesg

various fixes and improvements suggested by Linus.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 8d3b7a9..fded376 100644 (file)
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -108,6 +108,9 @@ extern struct resource iomem_resource;
 
 extern int request_resource(struct resource *root, struct resource *new);
 extern int release_resource(struct resource *new);
+extern void reserve_region_with_split(struct resource *root,
+                            resource_size_t start, resource_size_t end,
+                            const char *name);
 extern int insert_resource(struct resource *parent, struct resource *new);
 extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new);
 extern int allocate_resource(struct resource *root, struct resource *new,

diff --git a/kernel/resource.c b/kernel/resource.c
index 03d796c..414d6fc 100644 (file)
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -516,6 +516,74 @@ int adjust_resource(struct resource *res, resource_size_t start, resource_size_t
        return result;
 }
 
+static void __init __reserve_region_with_split(struct resource *root,
+               resource_size_t start, resource_size_t end,
+               const char *name)
+{
+       struct resource *parent = root;
+       struct resource *conflict;
+       struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);
+
+       if (!res)
+               return;
+
+       res->name = name;
+       res->start = start;
+       res->end = end;
+       res->flags = IORESOURCE_BUSY;
+
+       for (;;) {
+               conflict = __request_resource(parent, res);
+               if (!conflict)
+                       break;
+               if (conflict != parent) {
+                       parent = conflict;
+                       if (!(conflict->flags & IORESOURCE_BUSY))
+                               continue;
+               }
+
+               /* Uhhuh, that didn't work out.. */
+               kfree(res);
+               res = NULL;
+               break;
+       }
+
+       if (!res) {
+               printk(KERN_DEBUG "    __reserve_region_with_split: (%s) [%llx, %llx], res: (%s) [%llx, %llx]\n",
+                        conflict->name, conflict->start, conflict->end,
+                        name, start, end);
+
+               /* failed, split and try again */
+
+               /* conflict coverred whole area */
+               if (conflict->start <= start && conflict->end >= end)
+                       return;
+
+               if (conflict->start > start)
+                       __reserve_region_with_split(root, start, conflict->start-1, name);
+               if (!(conflict->flags & IORESOURCE_BUSY)) {
+                       resource_size_t common_start, common_end;
+
+                       common_start = max(conflict->start, start);
+                       common_end = min(conflict->end, end);
+                       if (common_start < common_end)
+                               __reserve_region_with_split(root, common_start, common_end, name);
+               }
+               if (conflict->end < end)
+                       __reserve_region_with_split(root, conflict->end+1, end, name);
+       }
+
+}
+
+void reserve_region_with_split(struct resource *root,
+               resource_size_t start, resource_size_t end,
+               const char *name)
+{
+       write_lock(&resource_lock);
+       __reserve_region_with_split(root, start, end, name);
+       write_unlock(&resource_lock);
+}
+
 EXPORT_SYMBOL(adjust_resource);
 
 /**