[dpdk-dev] [PATCH v2] test/func_reentrancy: free memzones after creating test case

[Joyce Kong]

<snip>

> > > Subject: Re: [dpdk-dev] [PATCH v2] test/func_reentrancy: free
> > > memzones after creating test case
> > >
> > > On Sat, Jul 31, 2021 at 2:04 PM Joyce Kong <joyce.kong at arm.com> wrote:
> > > >
> > > > Function reentrancy test limits maximum number of iterations
> > > > simultaneously, however it doesn't free the 'fr_test_once'
> > > > memzones after the fact, so introduce freeing 'fr_test_once'
> > > > in ring/mempool/hash/fbk/lpm_clean.
> > > >
> > > > Meanwhile, add the missing free for test case on main thread.
> > > >
> > > > Fixes: 104a92bd026f ("app: add reentrancy tests")
> > > > Fixes: 995eec619024 ("test: clean up memory for function
> > > > reentrancy
> > > > test")
> > > > Cc: stable at dpdk.org
> > > >
> > > > Signed-off-by: Joyce Kong <joyce.kong at arm.com>
> > > > Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> > > > Reviewed-by: Feifei Wang <feifei.wang2 at arm.com>
> > >
> > > This patch actually breaks the test (we are lucky, the failure happens
> often ;)).
> > >
> > > 28/94 DPDK:fast-tests / func_reentrancy_autotest       FAIL
> > > 0.22s (exit status 255 or signal 127 SIGinvalid)
> > >
> > > --- command ---
> > > 16:13:45 DPDK_TEST='func_reentrancy_autotest'
> > > /home-local/jenkins-local/jenkins-agent/workspace/Generic-Unit-Test-
> > > DPDK/dpdk/build/app/test/dpdk-test
> > > -l 0-15 --file-prefix=func_reentrancy_autotest
> > > --- stdout ---
> > > RTE>>func_reentrancy_autotest
> > > Func-ReEnt CASE 0: eal init once PASS ring create/lookup: common
> > > object allocated 2 times (should be 1) Func- ReEnt CASE 1: ring
> > > create/lookup FAIL Test Failed
> > > RTE>>
> > > --- stderr ---
> > >
> > >
> > > I guess, this is what happens:
> > >
> > > main lcore                          worker lcore 1              ...
> > > worker lcore X
> > >                                     enters ring_create_lookup()
> > >
> > > enters ring_create_lookup()
> > > rte_eal_wait_lcore(worker lcore 1);
> > >                                     leaves ring_create_lookup()
> > > ring_clean(worker lcore 1);
> > >
> > > leaves ring_create_lookup()
> > >
> > > There is no synchronisation point for the main lcore to know the
> > > worker lcores are finished invoking the func callback.
> > > With this patch, the "common" object is freed by the main lcore
> > > *potentially* before some workers start trying to create it.
> > > And we end up with multiple workers successfully creating this
> > > object, hence the obj_count being incremented.
> > >
> > >
> > > --
> > > David Marchand
> >
> > I think add rte_eal_mp_wait_lcore() like below can ensure the lcores
> > to free objects after all func callback finished.
> > Shall do the change in next version.
> >
> >         RTE_LCORE_FOREACH_WORKER(lcore_id) {
> >                 if (cores == 1)
> >                         break;
> >                 cores--;
> >                 rte_eal_remote_launch(pt_case->func, pt_case->arg, lcore_id);
> >         }
> >         rte_atomic32_set(&synchro, 1);
> >         if (pt_case->func(pt_case->arg) < 0)
> >                 ret = -1;
> >
> > +       rte_eal_mp_wait_lcore();
> >
> >         cores = cores_save;
> >         RTE_LCORE_FOREACH_WORKER(lcore_id) {
> >                 if (cores == 1)
> >                         break;
> >                 cores--;
> > -               if (rte_eal_wait_lcore(lcore_id) < 0)
> > -                       ret = -1;
> >                 if (pt_case->clean != NULL)
> >                         pt_case->clean(lcore_id);
> >         }
> 
> Using mp_wait_lcore, the test can't tell if a lcore returned an error after
> executing the passed callback.
> 
> An alternative is to split the current loop to first have the per lcore
> rte_eal_wait_lcore() calls + ret code check, and then a second loop calls the
> clean() callback.
> 
> 
> --
> David Marchand

Hi, David, thanks for your suggestion, will send a new version with this modification.

--
Joyce