[PATCH v2] service: fix deadlock on worker lcore exit

[David Marchand]

On Thu, Oct 3, 2024 at 5:50 PM Van Haaren, Harry
<harry.van.haaren at intel.com> wrote:
> > From: David Marchand <david.marchand at redhat.com>
> > Sent: Thursday, October 3, 2024 10:13 AM
> > To: Mattias Rönnblom <mattias.ronnblom at ericsson.com>; Van Haaren, Harry <harry.van.haaren at intel.com>
> > Cc: dev at dpdk.org <dev at dpdk.org>; stephen at networkplumber.org <stephen at networkplumber.org>; suanmingm at nvidia.com <suanmingm at nvidia.com>; thomas at monjalon.net <thomas at monjalon.net>; stable at dpdk.org <stable at dpdk.org>; Tyler Retzlaff <roretzla at linux.microsoft.com>; Aaron Conole <aconole at redhat.com>
> > Subject: Re: [PATCH v2] service: fix deadlock on worker lcore exit
> >
> > On Thu, Oct 3, 2024 at 8:57 AM David Marchand <david.marchand at redhat.com> wrote:
> > >
> > > From: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
> > >
> > > Calling rte_exit() from a worker lcore thread causes a deadlock in
> > > rte_service_finalize().
> > >
> > > This patch makes rte_service_finalize() deadlock-free by avoiding the
> > > need to synchronize with service lcore threads, which in turn is
> > > achieved by moving service and per-lcore state from the heap to being
> > > statically allocated.
> > >
> > > The BSS segment increases with ~156 kB (on x86_64 with default
> > > RTE_MAX_LCORE and RTE_SERVICE_NUM_MAX).
> > >
> > > According to the service perf autotest, this change also results in a
> > > slight reduction of service framework overhead.
> > >
> > > Fixes: 33666b448f15 ("service: fix crash on exit")
> > > Cc: stable at dpdk.org
> > >
> > > Signed-off-by: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
> > > Acked-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
> > > ---
> > > Changes since v1:
> > > - rebased,
> >
> > I can't merge this patch in its current state.
> >
> > At the moment, two CI report a problem with the
> > eal_flags_file_prefix_autotest unit test.
> >
> > -------------------------------------stdout-------------------------------------
> > RTE>>eal_flags_file_prefix_autotest
> > Running binary with argv[]:'/home/zhoumin/gh_dpdk/build/app/dpdk-test'
> > '--proc-type=secondary' '-m' '18' '--file-prefix=memtest'
> > Running binary with argv[]:'/home/zhoumin/gh_dpdk/build/app/dpdk-test'
> > '-m' '18' '--file-prefix=memtest1'
> > Error - hugepage files for memtest1 were not deleted!
> > Test Failed
> > RTE>>
> >
> > Can you have a look?
>
> Not sure how the code change in question is relating to the eal-flags failure, but I can reproduce the failure here.
> Reproducing issue on *all* of the below tags; this indicates its likely a board-config issue, and not a true issue (unless its been there since 23.11??).
>
> Tested commits were all bad:
> b3485f4293 (HEAD, tag: v24.07) version: 24.07.0
> a9778aad62 (HEAD, tag: v24.03) version: 24.03.0
> eeb0605f11 (HEAD, tag: v23.11) version: 23.11.0
>
> So I'm pretty sure this is a board/runner config issue, with the error output as follows here:
> RTE>>eal_flags_file_prefix_autotest
> Running binary with argv[]:'./app/test/dpdk-test' '--proc-type=secondary' '-m' '18' '--file-prefix=memtest'
> EAL: Detected CPU lcores: 64
> EAL: Detected NUMA nodes: 2
> EAL: Detected static linkage of DPDK
> EAL: Cannot open '/var/run/dpdk/memtest/config' for rte_mem_config
> EAL: FATAL: Cannot init config
> EAL: Cannot init config
>
> FAIL:
> DPDK_TEST=eal_flags_file_prefix_autotest ./app/test/dpdk-test  --no-pci
>
> PASS:
> DPDK_TEST=eal_flags_file_prefix_autotest ./app/test/dpdk-test
>
> So seems like the eal-flags test is NOT able to handle args like "--no-pci"? I tend to run tests in no PCI mode to speed up things :)

Well, speeding up, or hiding the issue, I guess.

> In short, this service-cores patch is not the root cause. Perhaps some of the CI folks can confirm if there's extra args passed to the runner?

To be clear, I can't merge this patch because of this (systematic)
failure in many CI env (GHA, LoongArch, UNH).

Adding CI ml in the loop.


-- 
David Marchand