[PATCHv3 2/5] lib/genalloc.c: Add genpool range check function

On 6/20/2014 2:38 AM, Will Deacon wrote:

On Tue, Jun 17, 2014 at 02:39:22AM +0100, Laura Abbott wrote:

quoted

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 <redacted>
---
 include/linux/genalloc.h |  3 +++
 lib/genalloc.c           | 29 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 3cd0934..1ccaab4 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h

@@ -121,6 +121,9 @@ extern struct gen_pool *devm_gen_pool_create(struct device *dev,
 		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);

diff --git a/lib/genalloc.c b/lib/genalloc.c
index 9758529..66edf93 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c

@@ -403,6 +403,35 @@ void gen_pool_for_each_chunk(struct gen_pool *pool,
 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. Takes
+ * the rcu_read_lock for the duration of the check.
+ */
+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) {

Why do you need to check start against the end of the chunk? Is that in case
of overflow?

Yes, this provides an extra check for overflow and also matches similar logic for
gen_pool_virt_to_phys.

Thanks,
Laura

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