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