eal: fix check when retrieving current cpu affinity

  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(-)
  

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?
  

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.
  

On 14-Feb-19 5:41 PM, David Marchand wrote:
> 
> 
> On Thu, Feb 14, 2019 at 5:44 PM Burakov, Anatoly 
> <anatoly.burakov@intel.com <mailto: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
>     <mailto: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.
> 

You're incorrectly handling error condition - that's a bug regardless of 
how likely it is to occur :)
  

On Tue, Feb 19, 2019 at 12:40 PM Burakov, Anatoly <anatoly.burakov@intel.com>
wrote:

> On 14-Feb-19 5:41 PM, David Marchand wrote:
> > On Thu, Feb 14, 2019 at 5:44 PM Burakov, Anatoly
> > <anatoly.burakov@intel.com <mailto:anatoly.burakov@intel.com>> wrote:
> >     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.
> >
>
> You're incorrectly handling error condition - that's a bug regardless of
> how likely it is to occur :)
>

Ok will resend with Cc: