lib/genalloc.c: add genpool range check function

After allocating an address from a particular genpool, there is no good
way to verify if that address actually belongs to a genpool. Introduce
addr_in_gen_pool which will return if an address plus size falls
completely within the genpool range.

Signed-off-by: Laura Abbott <[e-mail]>
Acked-by: Will Deacon <[e-mail]>
Reviewed-by: Olof Johansson <[e-mail]>
Reviewed-by: Catalin Marinas <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: David Riley <[e-mail]>
Cc: Ritesh Harjain <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Thierry Reding <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/genalloc.h

···
 		int min_alloc_order, int nid);
 extern struct gen_pool *dev_get_gen_pool(struct device *dev);
 
+bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
+			size_t size);
+
 #ifdef CONFIG_OF
 extern struct gen_pool *of_get_named_gen_pool(struct device_node *np,
 	const char *propname, int index);

lib/genalloc.c

···
 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 
 /**
+ * addr_in_gen_pool - checks if an address falls within the range of a pool
+ * @pool:	the generic memory pool
+ * @start:	start address
+ * @size:	size of the region
+ *
+ * Check if the range of addresses falls within the specified pool. Returns
+ * true if the entire range is contained in the pool and false otherwise.
+ */
+bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
+			size_t size)
+{
+	bool found = false;
+	unsigned long end = start + size;
+	struct gen_pool_chunk *chunk;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
+		if (start >= chunk->start_addr && start <= chunk->end_addr) {
+			if (end <= chunk->end_addr) {
+				found = true;
+				break;
+			}
+		}
+	}
+	rcu_read_unlock();
+	return found;
+}
+
+/**
  * gen_pool_avail - get available free space of the pool
  * @pool: pool to get available free space
  *