Re: [dpdk-dev] [PATCH] eal: fix check when retrieving current cpu affinity

[David Marchand <david.marchand@redhat.com>]

On Thu, Feb 14, 2019 at 5:44 PM Burakov, Anatoly <anatoly.burakov@intel.com>
wrote:

> On 14-Feb-19 1:27 PM, David Marchand wrote:
> > pthread_getaffinity_np returns a >0 value when failing.
> >
> > This is mainly for the sake of correctness.
> > The only case where it could fail is when passing an incorrect cpuset
> > size wrt to the kernel.
> >
> > Fixes: 2eba8d21f3c9 ("eal: restrict cores auto detection")
> > Signed-off-by: David Marchand <david.marchand@redhat.com>
> > ---
> >   lib/librte_eal/common/eal_common_options.c | 5 ++---
> >   1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/librte_eal/common/eal_common_options.c
> b/lib/librte_eal/common/eal_common_options.c
> > index 6c96f45..1f45f82 100644
> > --- a/lib/librte_eal/common/eal_common_options.c
> > +++ b/lib/librte_eal/common/eal_common_options.c
> > @@ -1343,10 +1343,9 @@ static int xdigit2val(unsigned char c)
> >       unsigned int lcore_id;
> >       unsigned int removed = 0;
> >       rte_cpuset_t affinity_set;
> > -     pthread_t tid = pthread_self();
> >
> > -     if (pthread_getaffinity_np(tid, sizeof(rte_cpuset_t),
> > -                             &affinity_set) < 0)
> > +     if (pthread_getaffinity_np(pthread_self(), sizeof(rte_cpuset_t),
> > +                             &affinity_set))
> >               CPU_ZERO(&affinity_set);
> >
> >       for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
> >
> CC: stable?
>

Not really sure about CCing stable for this.

I did not get errors with pthread_getaffinity_np so far.
Afaiu, it would need the kernel and libc to have different cpuset sizes.
I did not investigate in which situations it could happen.


-- 
David Marchand