[dpdk-dev] [PATCH v2 1/2] test/mempool_perf: Free mempool on exit

[santosh]

Hi Olivier,

On Monday 10 April 2017 12:47 AM, Shukla, Santosh wrote:

>
>
> --------------------------------------------------------------------------------
> *From:* Olivier Matz <olivier.matz at 6wind.com>
> *Sent:* Friday, April 7, 2017 9:21 PM
> *To:* Shukla, Santosh
> *Cc:* dev at dpdk.org; hemant.agrawal at nxp.com; shreyansh.jain at nxp.com; stable at dpdk.org
> *Subject:* Re: [PATCH v2 1/2] test/mempool_perf: Free mempool on exit
> Hi Santosh,
>
> On Thu,  6 Apr 2017 12:15:48 +0530, Santosh Shukla 
> <santosh.shukla at caviumnetworks.com> wrote:
> > Mempool_perf test not freeing pool memory.
> >
> > Cc: stable at dpdk.org
> > Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
> > Acked-by: Shreyansh Jain <shreyansh.jain at nxp.com>
> > ---
> > v1 --> v2:
> >  * Fixed patch context
> >
> >  test/test/test_mempool_perf.c | 31 +++++++++++++++++++------------
> >  1 file changed, 19 insertions(+), 12 deletions(-)
> >
> > diff --git a/test/test/test_mempool_perf.c b/test/test/test_mempool_perf.c
> > index ebf1721ac..3c45971ab 100644
> > --- a/test/test/test_mempool_perf.c
> > +++ b/test/test/test_mempool_perf.c
> > @@ -312,6 +312,8 @@ do_one_mempool_test(unsigned cores)
> >  static int
> >  test_mempool_perf(void)
> >  {
> > +     int ret = -1;
> > +
> >        rte_atomic32_init(&synchro);
> >
> >        /* create a mempool (without cache) */
> > @@ -322,7 +324,7 @@ test_mempool_perf(void)
> >                                                my_obj_init, NULL,
> >                                                SOCKET_ID_ANY, 0);
> >        if (mp_nocache == NULL)
> > -             return -1;
> > +             goto err;
> >
> >        /* create a mempool (with cache) */
> >        if (mp_cache == NULL)
>
> [...]
>
> >
> > -     return 0;
> > +     ret = 0;
> > +
> > +err:
> > +     rte_mempool_free(mp_cache);
> > +     rte_mempool_free(mp_nocache);
> > +     return ret;
>
>
> Since mp_cache and mp_nocache are global variables, this won't
> work properly due to the way mempool are created:
>
>          /* create a mempool (without cache) */
>          if (mp_nocache == NULL)
>                  mp_nocache = rte_mempool_create("perf_test_nocache", MEMPOOL_SIZE,
>                                                  MEMPOOL_ELT_SIZE, 0, 0,
>                                                  NULL, NULL,
>                                                  my_obj_init, NULL,
>                                                  SOCKET_ID_ANY, 0);
>
> The if() should be removed, else we'll have a use after free the next
> time.

I understand your point.
But I think problem is rte_mempool_free() not referencing mp = null
after freeing resources. Result of that is mp_nocache still has valid 
address, Although internal resources (mz/_ops_handle) were actually freed by
rte_mempool_free(), right?

So rather removing above if(), why not
- Application explicit set mp_nocache = NULL after mempool_free().
ie.. 

err:
	rte_mempool_free(xxx);
	xxx = NULL;


Or
- Let rte_mempool_free() { - do mp = null; }

And yes remove that if condition anyway. As its a dead-code
 for either of above 2 options.

Does that make sense to you? If so then which one you prefer?

> If you want to do more clean-up, you can try to remove the global variables,
> but it's maybe harder.

Removing global var won't be harder imo, May be you know more but
here is my point of view, after going through code:

- All test_func like
do_one_mempool_test -> launch_cores --> per_lcore_mempool_test -> using 'mp'

where 'mp' is global. 

how about,
- As you said Yes - remove global var ie.. mp_cache/nocache, default_pool, mp
- Add 'rte_mempool *mp' as argument in do_one_mempool_test() func and other func too.

Thus get rid of globals from app.

Does that make sense to you? 

Thanks,.
Santosh

> Thanks,
> Olivier