lib: genalloc: Add API to allocate at specified addr.

Add API to allocate at specified alloc address.

Change-Id: I188e5430220c050026c6a3e17a586012d9a9fa04
Signed-off-by: Krishna Reddy <[email protected]>
Reviewed-on: http://git-master/r/74468
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Stephen Warren <[email protected]>

Author: Krishna Reddy

include/linux/genalloc.h

@@ -72,7 +72,17 @@ static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
 	return gen_pool_add_virt(pool, addr, -1, size, nid);
 }
 extern void gen_pool_destroy(struct gen_pool *);
-extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
+extern unsigned long gen_pool_alloc_addr(struct gen_pool *,
+	size_t, unsigned long);
+/**
+ * gen_pool_alloc - allocate special memory from the pool
+ * @pool: pool to allocate from
+ * @size: number of bytes to allocate from the pool
+ */
+static inline unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
+{
+	return gen_pool_alloc_addr(pool, size);
+}
 extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
 extern void gen_pool_for_each_chunk(struct gen_pool *,
 	void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);

lib/genalloc.c

@@ -250,20 +250,23 @@ void gen_pool_destroy(struct gen_pool *pool)
 EXPORT_SYMBOL(gen_pool_destroy);
 
 /**
- * gen_pool_alloc - allocate special memory from the pool
+ * gen_pool_alloc_addr - allocate special memory from the pool
  * @pool: pool to allocate from
  * @size: number of bytes to allocate from the pool
+ * @alloc_addr: if non-zero, allocate starting at alloc_addr.
  *
  * Allocate the requested number of bytes from the specified pool.
  * Uses a first-fit algorithm. Can not be used in NMI handler on
  * architectures without NMI-safe cmpxchg implementation.
  */
-unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
+unsigned long gen_pool_alloc_addr(struct gen_pool *pool, size_t size,
+				    unsigned long alloc_addr)
 {
 	struct gen_pool_chunk *chunk;
 	unsigned long addr = 0;
 	int order = pool->min_alloc_order;
 	int nbits, start_bit = 0, end_bit, remain;
+	int alloc_bit_needed = 0;
 
 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 	BUG_ON(in_nmi());
@@ -272,16 +275,30 @@ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 	if (size == 0)
 		return 0;
 
+	if (alloc_addr & (1 << order) - 1)
+		return 0;
+
 	nbits = (size + (1UL << order) - 1) >> order;
 	rcu_read_lock();
 	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 		if (size > atomic_read(&chunk->avail))
 			continue;
 
 		end_bit = (chunk->end_addr - chunk->start_addr) >> order;
+		if (alloc_addr) {
+			if (alloc_addr < chunk->start_addr ||
+				alloc_addr >= chunk->end_addr)
+				continue;
+			if (alloc_addr + size > chunk->end_addr)
+				return 0;
+			alloc_bit_needed = start_bit =
+				(alloc_addr - chunk->start_addr) >> order;
+		}
 retry:
 		start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit,
 						       start_bit, nbits, 0);
+		if (alloc_addr && alloc_bit_needed != start_bit)
+			return 0;
 		if (start_bit >= end_bit)
 			continue;
 		remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
@@ -300,7 +317,7 @@ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 	rcu_read_unlock();
 	return addr;
 }
-EXPORT_SYMBOL(gen_pool_alloc);
+EXPORT_SYMBOL(gen_pool_alloc_addr);
 
 /**
  * gen_pool_free - free allocated special memory back to the pool