[dpdk-dev] mempool: fix the inverted pg_num check on create

  The rest of the code expects pg_num <= RTE_DIM(mp->elt_pa).

Signed-off-by: Dan Aloni <dan@kernelim.com>
---
 lib/librte_mempool/rte_mempool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
  

Hi,

On 08/16/2015 09:08 PM, Dan Aloni wrote:
> The rest of the code expects pg_num <= RTE_DIM(mp->elt_pa).
> 
> Signed-off-by: Dan Aloni <dan@kernelim.com>
> ---
>  lib/librte_mempool/rte_mempool.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 8e185c545479..edcfa8bf9cb1 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -461,7 +461,7 @@ rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
>  	}
>  
>  	/* Check that pg_num and pg_shift parameters are valid. */
> -	if (pg_num < RTE_DIM(mp->elt_pa) || pg_shift > MEMPOOL_PG_SHIFT_MAX) {
> +	if (pg_num > RTE_DIM(mp->elt_pa) || pg_shift > MEMPOOL_PG_SHIFT_MAX) {
>  		rte_errno = EINVAL;
>  		return NULL;
>  	}
> 


Could you give some details about the conditions to reproduce and the
consequences of the issue?

From what I see, RTE_DIM(mp->elt_pa) is always 1:

	#define MEMPOOL_PG_NUM_DEFAULT  1
	struct rte_mempool {
		...
	        phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
	}  __rte_cache_aligned;

From rte_mempool_xmem_create() documentation, pg_num gives the size of
the paddr array, which is allocated by the caller. So I think there is
no issue here.

Regards,
Olivier
  

On Mon, Aug 17, 2015 at 10:55:35AM +0200, Olivier MATZ wrote:
> On 08/16/2015 09:08 PM, Dan Aloni wrote:
[..]
> >  	/* Check that pg_num and pg_shift parameters are valid. */
> > -	if (pg_num < RTE_DIM(mp->elt_pa) || pg_shift > MEMPOOL_PG_SHIFT_MAX) {
> > +	if (pg_num > RTE_DIM(mp->elt_pa) || pg_shift > MEMPOOL_PG_SHIFT_MAX) {
> >  		rte_errno = EINVAL;
> >  		return NULL;

> 
> From what I see, RTE_DIM(mp->elt_pa) is always 1:
> 
> 	#define MEMPOOL_PG_NUM_DEFAULT  1
> 	struct rte_mempool {
> 		...
> 	        phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
> 	}  __rte_cache_aligned;
> 
> From rte_mempool_xmem_create() documentation, pg_num gives the size of
> the paddr array, which is allocated by the caller. So I think there is
> no issue here.

You're right, I missed on the fact that mempool takes pg_num as its
run-time determined size of the array for both its dynamically allocated
copy and the caller's provided array.

The MEMPOOL_PG_NUM_DEFAULT macro is was a bit distracting in this. I
wanted to provide pg_num > 1 and it wasn't clear on whether to modify
the macro, or simply call the function :). So, never mind the patch.