参照元

説明

引数

返り値

参考

実装

/*
 * Allocate a region of KVA of the specified size and alignment, within the
 * vstart and vend.
 */
static struct vmap_area *alloc_vmap_area(unsigned long size,
				unsigned long align,
				unsigned long vstart, unsigned long vend,
				int node, gfp_t gfp_mask)
{
	struct vmap_area *va;
	struct rb_node *n;
	unsigned long addr;
	int purged = 0;
	BUG_ON(!size);
	BUG_ON(size & ~PAGE_MASK);
	va = kmalloc_node(sizeof(struct vmap_area),
			gfp_mask & GFP_RECLAIM_MASK, node);
	if (unlikely(!va))
		return ERR_PTR(-ENOMEM);
retry:
	addr = ALIGN(vstart, align);
	spin_lock(&vmap_area_lock);
	if (addr + size - 1 < addr)
		goto overflow;

	/* XXX: could have a last_hole cache */
	n = vmap_area_root.rb_node;
	if (n) {
		struct vmap_area *first = NULL;

		do {
			struct vmap_area *tmp;
			tmp = rb_entry(n, struct vmap_area, rb_node);
			if (tmp->va_end >= addr) {
				if (!first && tmp->va_start < addr + size)
					first = tmp;
				n = n->rb_left;
			} else {
				first = tmp;
				n = n->rb_right;
			}
		} while (n);

		if (!first)
			goto found;

		if (first->va_end < addr) {
			n = rb_next(&first->rb_node);
			if (n)
				first = rb_entry(n, struct vmap_area, rb_node);
			else
				goto found;
		}

		while (addr + size > first->va_start && addr + size <= vend) {
			addr = ALIGN(first->va_end + PAGE_SIZE, align);
			if (addr + size - 1 < addr)
				goto overflow;

			n = rb_next(&first->rb_node);
			if (n)
				first = rb_entry(n, struct vmap_area, rb_node);
			else
				goto found;
		}
	}
found:
	if (addr + size > vend) {
overflow:
		spin_unlock(&vmap_area_lock);
		if (!purged) {
			purge_vmap_area_lazy();
			purged = 1;
			goto retry;
		}
		if (printk_ratelimit())
			printk(KERN_WARNING
				"vmap allocation for size %lu failed: "
				"use vmalloc=<size> to increase size.\n", size);
		kfree(va);
		return ERR_PTR(-EBUSY);
	}

	BUG_ON(addr & (align-1));

	va->va_start = addr;
	va->va_end = addr + size;
	va->flags = 0;
	__insert_vmap_area(va);
	spin_unlock(&vmap_area_lock);
	return va;
}

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Last-modified: 2014-09-13 (土) 08:26:40