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resource: ability to resize an allocated resource

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Provides the ability to resize a resource that is already allocated.
This functionality is put in place to support reallocation needs of
pci resources.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ram Pai 2011-07-05 23:44:30 -07:00 committed by Linus Torvalds
parent a51cb91d81
commit 23c570a674
1 changed files with 98 additions and 18 deletions
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116
kernel/resource.c
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@ -38,6 +38,14 @@ struct resource iomem_resource = {
};
EXPORT_SYMBOL(iomem_resource);
/* constraints to be met while allocating resources */
struct resource_constraint {
resource_size_t min, max, align;
resource_size_t (*alignf)(void *, const struct resource *,
resource_size_t, resource_size_t);
void *alignf_data;
};
static DEFINE_RWLOCK(resource_lock);
static void *r_next(struct seq_file *m, void *v, loff_t *pos)
@ -384,16 +392,13 @@ static bool resource_contains(struct resource *res1, struct resource *res2)
}
/*
* Find empty slot in the resource tree given range and alignment.
* Find empty slot in the resource tree with the given range and
* alignment constraints
*/
static int find_resource(struct resource *root, struct resource *new,
resource_size_t size, resource_size_t min,
resource_size_t max, resource_size_t align,
resource_size_t (*alignf)(void *,
const struct resource *,
resource_size_t,
resource_size_t),
void *alignf_data)
static int __find_resource(struct resource *root, struct resource *old,
struct resource *new,
resource_size_t size,
struct resource_constraint *constraint)
{
struct resource *this = root->child;
struct resource tmp = *new, avail, alloc;
@ -404,25 +409,26 @@ static int find_resource(struct resource *root, struct resource *new,
* Skip past an allocated resource that starts at 0, since the assignment
* of this->start - 1 to tmp->end below would cause an underflow.
*/
if (this && this->start == 0) {
tmp.start = this->end + 1;
if (this && this->start == root->start) {
tmp.start = (this == old) ? old->start : this->end + 1;
this = this->sibling;
}
for(;;) {
if (this)
tmp.end = this->start - 1;
tmp.end = (this == old) ? this->end : this->start - 1;
else
tmp.end = root->end;
resource_clip(&tmp, min, max);
resource_clip(&tmp, constraint->min, constraint->max);
arch_remove_reservations(&tmp);
/* Check for overflow after ALIGN() */
avail = *new;
avail.start = ALIGN(tmp.start, align);
avail.start = ALIGN(tmp.start, constraint->align);
avail.end = tmp.end;
if (avail.start >= tmp.start) {
alloc.start = alignf(alignf_data, &avail, size, align);
alloc.start = constraint->alignf(constraint->alignf_data, &avail,
size, constraint->align);
alloc.end = alloc.start + size - 1;
if (resource_contains(&avail, &alloc)) {
new->start = alloc.start;
@ -432,14 +438,75 @@ static int find_resource(struct resource *root, struct resource *new,
}
if (!this)
break;
tmp.start = this->end + 1;
if (this != old)
tmp.start = this->end + 1;
this = this->sibling;
}
return -EBUSY;
}
/*
* Find empty slot in the resource tree given range and alignment.
*/
static int find_resource(struct resource *root, struct resource *new,
resource_size_t size,
struct resource_constraint *constraint)
{
return __find_resource(root, NULL, new, size, constraint);
}
/**
* allocate_resource - allocate empty slot in the resource tree given range & alignment
* reallocate_resource - allocate a slot in the resource tree given range & alignment.
* The resource will be relocated if the new size cannot be reallocated in the
* current location.
*
* @root: root resource descriptor
* @old: resource descriptor desired by caller
* @newsize: new size of the resource descriptor
* @constraint: the size and alignment constraints to be met.
*/
int reallocate_resource(struct resource *root, struct resource *old,
resource_size_t newsize,
struct resource_constraint *constraint)
{
int err=0;
struct resource new = *old;
struct resource *conflict;
write_lock(&resource_lock);
if ((err = __find_resource(root, old, &new, newsize, constraint)))
goto out;
if (resource_contains(&new, old)) {
old->start = new.start;
old->end = new.end;
goto out;
}
if (old->child) {
err = -EBUSY;
goto out;
}
if (resource_contains(old, &new)) {
old->start = new.start;
old->end = new.end;
} else {
__release_resource(old);
*old = new;
conflict = __request_resource(root, old);
BUG_ON(conflict);
}
out:
write_unlock(&resource_lock);
return err;
}
/**
* allocate_resource - allocate empty slot in the resource tree given range & alignment.
* The resource will be reallocated with a new size if it was already allocated
* @root: root resource descriptor
* @new: resource descriptor desired by caller
* @size: requested resource region size
@ -459,12 +526,25 @@ int allocate_resource(struct resource *root, struct resource *new,
void *alignf_data)
{
int err;
struct resource_constraint constraint;
if (!alignf)
alignf = simple_align_resource;
constraint.min = min;
constraint.max = max;
constraint.align = align;
constraint.alignf = alignf;
constraint.alignf_data = alignf_data;
if ( new->parent ) {
/* resource is already allocated, try reallocating with
the new constraints */
return reallocate_resource(root, new, size, &constraint);
}
write_lock(&resource_lock);
err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
err = find_resource(root, new, size, &constraint);
if (err >= 0 && __request_resource(root, new))
err = -EBUSY;
write_unlock(&resource_lock);