[PATCH] x86: split e820 reserved entries record to late v4 - fix

[PATCH] x86: split e820 reserved entries record to late v4 - fix

[Yinghai Lu]

try to insert_resource second time, by expand the resource...

for case: e820 reserved entry is partially overlapped with bar res...

hope it will never happen

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

---
 arch/x86/kernel/e820.c |   32 ++++++++++++++++++++++++++++++--
 include/linux/ioport.h |    1 +
 kernel/resource.c      |   35 ++++++++++++++++++++++++++---------
 3 files changed, 57 insertions(+), 11 deletions(-)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -1319,8 +1319,36 @@ void __init e820_reserve_resources_late(
 
 	res = e820_res;
 	for (i = 0; i < e820.nr_map; i++) {
-		if (!res->parent && res->end)
-			insert_resource(&iomem_resource, res);
+		if (!res->parent && res->end) {
+			struct resource *ret;
+
+			ret = __insert_resource(&iomem_resource, res);
+			if (ret) {
+				int updated = 0;
+
+				printk(KERN_WARNING "found conflict: %s [%08llx, %08llx] with %s [%08llx, %08llx]\n",
+					res->name, res->start, res->end,
+					ret->name, ret->start, ret->end);
+				if (res->start > ret->start && res->start <= ret->end) {
+					if (i && ret->start > e820_res[i-1].end) {
+						res->start = ret->start;
+						updated = 1;
+					}
+				} else if (res->end > ret->start && res->end <= ret->end) {
+					if (i < (e820.nr_map - 1) && ret->end > e820_res[i+1].start) {
+						res->end = ret->end;
+						updated = 1;
+					}
+				}
+				if (updated) {
+					ret = __insert_resource(&iomem_resource, res);
+					if (ret)
+						printk(KERN_WARNING "second try found conflict: %s [%08llx, %08llx] with %s [%08llx, %08llx]\n",
+							res->name, res->start, res->end,
+							ret->name, ret->start, ret->end);
+				}
+			}
+		}
 		res++;
 	}
 }
Index: linux-2.6/include/linux/ioport.h
===================================================================
--- linux-2.6.orig/include/linux/ioport.h
+++ linux-2.6/include/linux/ioport.h
@@ -108,6 +108,7 @@ extern struct resource iomem_resource;
 
 extern int request_resource(struct resource *root, struct resource *new);
 extern int release_resource(struct resource *new);
+extern struct resource *__insert_resource(struct resource *parent, struct resource *new);
 extern int insert_resource(struct resource *parent, struct resource *new);
 extern int allocate_resource(struct resource *root, struct resource *new,
 			     resource_size_t size, resource_size_t min,
Index: linux-2.6/kernel/resource.c
===================================================================
--- linux-2.6.orig/kernel/resource.c
+++ linux-2.6/kernel/resource.c
@@ -363,11 +363,11 @@ int allocate_resource(struct resource *r
 EXPORT_SYMBOL(allocate_resource);
 
 /**
- * insert_resource - Inserts a resource in the resource tree
+ * __insert_resource - Inserts a resource in the resource tree
  * @parent: parent of the new resource
  * @new: new resource to insert
  *
- * Returns 0 on success, -EBUSY if the resource can't be inserted.
+ * Returns NULL on success, or first conflict resource.
  *
  * This function is equivalent to request_resource when no conflict
  * happens. If a conflict happens, and the conflicting resources
@@ -375,20 +375,20 @@ EXPORT_SYMBOL(allocate_resource);
  * resource is inserted and the conflicting resources become children of
  * the new resource.
  */
-int insert_resource(struct resource *parent, struct resource *new)
+struct resource *__insert_resource(struct resource *parent, struct resource *new)
 {
-	int result;
+	struct resource *ret_res;
 	struct resource *first, *next;
 
 	write_lock(&resource_lock);
 
 	for (;; parent = first) {
-	 	result = 0;
+		ret_res = NULL;
 		first = __request_resource(parent, new);
 		if (!first)
 			goto out;
 
-		result = -EBUSY;
+		ret_res = first;
 		if (first == parent)
 			goto out;
 
@@ -400,15 +400,17 @@ int insert_resource(struct resource *par
 
 	for (next = first; ; next = next->sibling) {
 		/* Partial overlap? Bad, and unfixable */
-		if (next->start < new->start || next->end > new->end)
+		if (next->start < new->start || next->end > new->end) {
+			ret_res = next;
 			goto out;
+		}
 		if (!next->sibling)
 			break;
 		if (next->sibling->start > new->end)
 			break;
 	}
 
-	result = 0;
+	ret_res = NULL;
 
 	new->parent = parent;
 	new->sibling = next->sibling;
@@ -429,10 +431,25 @@ int insert_resource(struct resource *par
 
  out:
 	write_unlock(&resource_lock);
-	return result;
+	return ret_res;
 }
 
 /**
+ * insert_resource - Inserts a resource in the resource tree
+ * @parent: parent of the new resource
+ * @new: new resource to insert
+ *
+ * Returns 0 on success, -EBUSY if the resource can't be inserted.
+ */
+int insert_resource(struct resource *parent, struct resource *new)
+{
+	struct resource *res_conflict;
+
+	res_conflict = __insert_resource(parent, new);
+
+	return res_conflict ? -EBUSY : 0;
+}
+/**
  * adjust_resource - modify a resource's start and size
  * @res: resource to modify
  * @start: new start value

Re: [PATCH] x86: split e820 reserved entries record to late v4 - fix

[Yinghai Lu]

On Fri, Aug 29, 2008 at 1:13 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
> try to insert_resource second time, by expand the resource...
>
> for case: e820 reserved entry is partially overlapped with bar res...
>
> hope it will never happen
>
> Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
>
> ---
>  arch/x86/kernel/e820.c |   32 ++++++++++++++++++++++++++++++--
>  include/linux/ioport.h |    1 +
>  kernel/resource.c      |   35 ++++++++++++++++++++++++++---------
>  3 files changed, 57 insertions(+), 11 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/e820.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/e820.c
> +++ linux-2.6/arch/x86/kernel/e820.c
> @@ -1319,8 +1319,36 @@ void __init e820_reserve_resources_late(
>
>        res = e820_res;
>        for (i = 0; i < e820.nr_map; i++) {
> -               if (!res->parent && res->end)
> -                       insert_resource(&iomem_resource, res);
> +               if (!res->parent && res->end) {
> +                       struct resource *ret;
> +
> +                       ret = __insert_resource(&iomem_resource, res);
> +                       if (ret) {
> +                               int updated = 0;
> +
> +                               printk(KERN_WARNING "found conflict: %s [%08llx, %08llx] with %s [%08llx, %08llx]\n",
> +                                       res->name, res->start, res->end,
> +                                       ret->name, ret->start, ret->end);
> +                               if (res->start > ret->start && res->start <= ret->end) {
> +                                       if (i && ret->start > e820_res[i-1].end) {
> +                                               res->start = ret->start;
> +                                               updated = 1;
> +                                       }
> +                               } else if (res->end > ret->start && res->end <= ret->end) {
> +                                       if (i < (e820.nr_map - 1) && ret->end > e820_res[i+1].start) {

should be
                                     if (i < (e820.nr_map - 1) &&
ret->end < e820_res[i+1].start) {

> +                                               res->end = ret->end;
> +                                               updated = 1;
> +                                       }
> +                               }
> +                               if (updated) {
> +                                       ret = __insert_resource(&iomem_resource, res);
> +                                       if (ret)
> +                                               printk(KERN_WARNING "second try found conflict: %s [%08llx, %08llx] with %s [%08llx, %08llx]\n",
> +                                                       res->name, res->start, res->end,
> +                                                       ret->name, ret->start, ret->end);
> +                               }
> +                       }
> +               }
>                res++;
>        }
>  }
> Index: linux-2.6/include/linux/ioport.h
> ===================================================================
> --- linux-2.6.orig/include/linux/ioport.h
> +++ linux-2.6/include/linux/ioport.h
> @@ -108,6 +108,7 @@ extern struct resource iomem_resource;
>
>  extern int request_resource(struct resource *root, struct resource *new);
>  extern int release_resource(struct resource *new);
> +extern struct resource *__insert_resource(struct resource *parent, struct resource *new);
>  extern int insert_resource(struct resource *parent, struct resource *new);
>  extern int allocate_resource(struct resource *root, struct resource *new,
>                             resource_size_t size, resource_size_t min,
> Index: linux-2.6/kernel/resource.c
> ===================================================================
> --- linux-2.6.orig/kernel/resource.c
> +++ linux-2.6/kernel/resource.c
> @@ -363,11 +363,11 @@ int allocate_resource(struct resource *r
>  EXPORT_SYMBOL(allocate_resource);
>
>  /**
> - * insert_resource - Inserts a resource in the resource tree
> + * __insert_resource - Inserts a resource in the resource tree
>  * @parent: parent of the new resource
>  * @new: new resource to insert
>  *
> - * Returns 0 on success, -EBUSY if the resource can't be inserted.
> + * Returns NULL on success, or first conflict resource.
>  *
>  * This function is equivalent to request_resource when no conflict
>  * happens. If a conflict happens, and the conflicting resources
> @@ -375,20 +375,20 @@ EXPORT_SYMBOL(allocate_resource);
>  * resource is inserted and the conflicting resources become children of
>  * the new resource.
>  */
> -int insert_resource(struct resource *parent, struct resource *new)
> +struct resource *__insert_resource(struct resource *parent, struct resource *new)
>  {
> -       int result;
> +       struct resource *ret_res;
>        struct resource *first, *next;
>
>        write_lock(&resource_lock);
>
>        for (;; parent = first) {
> -               result = 0;
> +               ret_res = NULL;
>                first = __request_resource(parent, new);
>                if (!first)
>                        goto out;
>
> -               result = -EBUSY;
> +               ret_res = first;
>                if (first == parent)
>                        goto out;
>
> @@ -400,15 +400,17 @@ int insert_resource(struct resource *par
>
>        for (next = first; ; next = next->sibling) {
>                /* Partial overlap? Bad, and unfixable */
> -               if (next->start < new->start || next->end > new->end)
> +               if (next->start < new->start || next->end > new->end) {
> +                       ret_res = next;
>                        goto out;
> +               }
>                if (!next->sibling)
>                        break;
>                if (next->sibling->start > new->end)
>                        break;
>        }
>
> -       result = 0;
> +       ret_res = NULL;
>
>        new->parent = parent;
>        new->sibling = next->sibling;
> @@ -429,10 +431,25 @@ int insert_resource(struct resource *par
>
>  out:
>        write_unlock(&resource_lock);
> -       return result;
> +       return ret_res;
>  }
>
>  /**
> + * insert_resource - Inserts a resource in the resource tree
> + * @parent: parent of the new resource
> + * @new: new resource to insert
> + *
> + * Returns 0 on success, -EBUSY if the resource can't be inserted.
> + */
> +int insert_resource(struct resource *parent, struct resource *new)
> +{
> +       struct resource *res_conflict;
> +
> +       res_conflict = __insert_resource(parent, new);
> +
> +       return res_conflict ? -EBUSY : 0;
> +}
> +/**
>  * adjust_resource - modify a resource's start and size
>  * @res: resource to modify
>  * @start: new start value
>

Re: [PATCH] x86: split e820 reserved entries record to late v4 - fix

[Linus Torvalds]

On Fri, 29 Aug 2008, Yinghai Lu wrote:
>
> try to insert_resource second time, by expand the resource...

I would hold off on this unless it's shown to actually be needed. And _if_ 
it is needed, I would just make a new function for doing this all: 
"insert_resource_expand_to_fit()"

That said, I think the insert_resource()/__insert_resource() change is 
pretty ok. However, it doesn't follow the rules, and is racy. The rules 
for resources are:

 - the "internal" version (with the "__" prepended) is static to 
   resource.c, because it must not be called from outside, which is in 
   turn because:

 - it must be called with the lock taken by the caller, because otherwise 
   returning a "struct resource *" is racy - the resource is not protected
   by anything!

So the "insert_resource_expand_to_fit()" thing would look something like 
this:

	void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
	{
		write_lock(&resource_lock);
		while (new->start && new->parent) {
			struct resource *conflict;

			conflict = __insert_resource(root, new);
			if (!conflict)
				break;
			if (conflict->start < new->start)
				new->start = conflict->start;
			if (conflict->end > new->end)
				new->end = conflict->end;
		}
		write_unlock(&resource_lock);
	}

but the above is obviously _totally_ untested.

		Linus

Re: [PATCH] x86: split e820 reserved entries record to late v4 - fix

[Yinghai Lu]

On Fri, Aug 29, 2008 at 9:05 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
>
> On Fri, 29 Aug 2008, Yinghai Lu wrote:
>>
>> try to insert_resource second time, by expand the resource...
>
> I would hold off on this unless it's shown to actually be needed. And _if_
> it is needed, I would just make a new function for doing this all:
> "insert_resource_expand_to_fit()"
>
> That said, I think the insert_resource()/__insert_resource() change is
> pretty ok. However, it doesn't follow the rules, and is racy. The rules
> for resources are:
>
>  - the "internal" version (with the "__" prepended) is static to
>   resource.c, because it must not be called from outside, which is in
>   turn because:
>
>  - it must be called with the lock taken by the caller, because otherwise
>   returning a "struct resource *" is racy - the resource is not protected
>   by anything!
>
> So the "insert_resource_expand_to_fit()" thing would look something like
> this:
>
>        void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
>        {
>                write_lock(&resource_lock);
>                while (new->start && new->parent) {
>                        struct resource *conflict;
>
>                        conflict = __insert_resource(root, new);
>                        if (!conflict)
>                                break;
>                        if (conflict->start < new->start)
>                                new->start = conflict->start;
>                        if (conflict->end > new->end)
>                                new->end = conflict->end;
>                }
>                write_unlock(&resource_lock);
>        }
>
> but the above is obviously _totally_ untested.
>

good, will build one test stub to test it.

YH

Re: [PATCH] x86: split e820 reserved entries record to late v4 - fix

[Linus Torvalds]

On Fri, 29 Aug 2008, Yinghai Lu wrote:
> >
> >        void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
> >        {
> >                write_lock(&resource_lock);
> >                while (new->start && new->parent) {

That should obviously be

	while (new->start && !new->parent) {
                            ^^^

oops.

I told you it was untested ;)

		Linus