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

Laura Abbott
2014-06-29T19:38:12Z

On 6/20/2014 2:38 AM, Will Deacon wrote:
> On Tue, Jun 17, 2014 at 02:39:22AM +0100, Laura Abbott wrote:
>> 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 <lauraa@codeaurora.org>
>> ---
>> 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

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,