Re: [dpdk-dev] [PATCH] eal: fix link status issue on ppc_64

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

Hello David,

On Tue, Oct 15, 2019 at 1:08 AM David Christensen
<drc@linux.vnet.ibm.com> wrote:
>
> The rte_atomic64_exchange operation for ppc_64 incorrectly linked
> back to a 32 bit generic operation (__atomic_exchange_4) rather than
> the 64 bit generic operation (__atomic_exchange_8).  As a result,
> only the link speed was passed to the application, not the link
> state, link duplex, on link autoneg properties.

Good catch.
The first impact is the link status, but you can imagine applications
calling this, so I would prefer a title like "eal/ppc: fix 64bits
exchange operation".
WDYT ?

rte_atomic64_exchange has no unit test.
This kind of problem could (should?) have been caught in unit tests.
Maybe something to add later.


>
> Fixes: ff2863570f ("eal: introduce atomic exchange operation")
> Cc: sthemmin@microsoft.com"
> Cc: stable@dpdk.org
>
> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
> ---
>  lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
> index b13a80de4..7e3e13118 100644
> --- a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
> +++ b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
> @@ -401,7 +401,7 @@ static inline void rte_atomic64_clear(rte_atomic64_t *v)
>  static inline uint64_t
>  rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val)
>  {
> -       return __atomic_exchange_4(dst, val, __ATOMIC_SEQ_CST);
> +       return __atomic_exchange_8(dst, val, __ATOMIC_SEQ_CST);
>  }
>
>  #endif
> --
> 2.18.1
>



-- 
David Marchand