Re: [dpdk-dev] [PATCH v4 1/3] net/iavf: fix segment fault in AVX512

["Lu, Wenzhuo" <wenzhuo.lu@intel.com>]

Hi Ferruh,

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Tuesday, April 13, 2021 8:37 PM
> To: Lu, Wenzhuo <wenzhuo.lu@intel.com>; dev@dpdk.org; Richardson,
> Bruce <bruce.richardson@intel.com>
> Cc: stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v4 1/3] net/iavf: fix segment fault in AVX512
> 
> On 4/9/2021 4:01 AM, Wenzhuo Lu wrote:
> > Fix segment fault when failing to get the memory from the pool.
> >
> 
> Can be good to clarify there is no change in the moved code, it is not possible
> to recognize this from patch without using a compare app.
Sure. Will add more description here.

> 
> > Fixes: 31737f2b66fb ("net/iavf: enable AVX512 for legacy Rx")
> > Cc: stable@dpdk.org
> >
> > Reported-by: David Coyle <David.Coyle@intel.com>
> > Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> > ---
> >   drivers/net/iavf/iavf_rxtx_vec_avx2.c   | 120 +------------------
> >   drivers/net/iavf/iavf_rxtx_vec_avx512.c |   5 +-
> >   drivers/net/iavf/iavf_rxtx_vec_common.h | 203
> > ++++++++++++++++++++++++++++++++
> 
> The common vector code seems moved to 'iavf_rxtx_vec_common.h' but
> that header is included by 'iavf_rxtx_vec_sse.c' too, and the moved function
> has AVX2 code in it.
> Won't this fail to build if the AVX2 is not enabled?
Agree. There may be a compile error. I'll change the ' RTE_ARCH_X86 ' to ' CC_AVX2_SUPPORT ' to make the code only for avx2 and avx512.

> 
> Bruce, is there an easy way to test this, meson detects the AVX2 support
> even I provide c_args march that doesn't have AVX2 support.
> 
> <...>
> 
> > index 46a1873..57b4381 100644
> > --- a/drivers/net/iavf/iavf_rxtx_vec_common.h
> > +++ b/drivers/net/iavf/iavf_rxtx_vec_common.h
> > @@ -11,6 +11,10 @@
> >   #include "iavf.h"
> >   #include "iavf_rxtx.h"
> >
> > +#ifndef __INTEL_COMPILER
> > +#pragma GCC diagnostic ignored "-Wcast-qual"
> > +#endif
> > +
> 
> Is this pragma needed or carried here to be sure?
It's necessary for a compile warning. Just leveraged from the existing code.

> 
> >   static inline uint16_t
> >   reassemble_packets(struct iavf_rx_queue *rxq, struct rte_mbuf **rx_bufs,
> >   		   uint16_t nb_bufs, uint8_t *split_flags) @@ -276,4 +280,203
> @@
> >   	return 0;
> >   }
> >
> > +#ifdef RTE_ARCH_X86
> > +static __rte_always_inline void
> > +iavf_rxq_rearm_cmn(struct iavf_rx_queue *rxq, __rte_unused bool
> > +avx512)
> 
> What do you think expand 'cmn' to full 'common', it is clear from this patch
> what it stands for but later if you just look this function it is not that clear if it
> is an abbreviation for something else or common.
Sure. Will change it to 'common'.