[dpdk-dev] [RFC] service: stop lcore threads before 'finalize'

[Van Haaren, Harry]

> -----Original Message-----
> From: Aaron Conole <aconole at redhat.com>
> Sent: Tuesday, February 4, 2020 2:51 PM
> To: David Marchand <david.marchand at redhat.com>
> Cc: Van Haaren, Harry <harry.van.haaren at intel.com>; dev <dev at dpdk.org>
> Subject: Re: [RFC] service: stop lcore threads before 'finalize'
> 
> David Marchand <david.marchand at redhat.com> writes:
> 
> > On Fri, Jan 17, 2020 at 9:17 AM David Marchand
> > <david.marchand at redhat.com> wrote:
> >>
> >> On Thu, Jan 16, 2020 at 8:50 PM Aaron Conole <aconole at redhat.com> wrote:
> >> >
> >> > I've noticed an occasional segfault from the build system in the
> >> > service_autotest and after talking with David (CC'd), it seems like
> it's
> >> > due to the rte_service_finalize deleting the lcore_states object while
> >> > active lcores are running.
> >> >
> >> > The below patch is an attempt to solve it by first reassigning all the
> >> > lcores back to ROLE_RTE before releasing the memory.  There is probably
> >> > a larger question for DPDK proper about actually closing the pending
> >> > lcore threads, but that's a separate issue.  I've been running with the
> >> > patch for a while, and haven't seen the crash anymore on my system.
> >> >
> >> > Thoughts?  Is it acceptable as-is?
> >>
> >> Added this patch to my env, still reproducing the same issue after ~10-20
> tries.
> >> I added a breakpoint to service_lcore_uninit that is indeed caught
> >> when exiting the test application (just wanted to make sure your
> >> change was in my binary).
> >
> > Harry,
> >
> > We need a fix for this issue.
> 
> +1

Hi All,

> > Interestingly, Stephen patch that joins all pthreads at
> > rte_eal_cleanup [1] makes this issue disappear.
> > So my understanding is that we are missing a api (well, I could not
> > find a way) to synchronously stop service lcores.
> 
> Maybe we can take that patch as a fix.  I hate to see this segfault
> in the field.  I need to figure out what I missed in my cleanup
> (probably missed a synchronization point).

I haven't easily reproduced this yet - so I'll investigate a way to 
reproduce with close to 100% rate, then we can identify the root cause
and actually get a clean fix. If you have pointers to reproduce easily,
please let me know.

-H

> > 1: https://patchwork.dpdk.org/patch/64201/