[EXT] Re: [PATCH v4 21/22] pdcp: add thread safe processing

[Anoob Joseph]

Hi Stephen,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: Stephen Hemminger <stephen at networkplumber.org>
> Sent: Saturday, May 27, 2023 3:42 AM
> To: Anoob Joseph <anoobj at marvell.com>
> Cc: Thomas Monjalon <thomas at monjalon.net>; Akhil Goyal
> <gakhil at marvell.com>; Jerin Jacob Kollanukkaran <jerinj at marvell.com>;
> Konstantin Ananyev <konstantin.v.ananyev at yandex.ru>; Volodymyr Fialko
> <vfialko at marvell.com>; Hemant Agrawal <hemant.agrawal at nxp.com>;
> Mattias Rönnblom <mattias.ronnblom at ericsson.com>; Kiran Kumar
> Kokkilagadda <kirankumark at marvell.com>; dev at dpdk.org; Olivier Matz
> <olivier.matz at 6wind.com>
> Subject: [EXT] Re: [PATCH v4 21/22] pdcp: add thread safe processing
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Sat, 27 May 2023 02:32:13 +0530
> Anoob Joseph <anoobj at marvell.com> wrote:
> 
> > +static inline uint32_t
> > +pdcp_atomic_inc(uint32_t *val, const bool mt_safe) {
> > +	if (mt_safe)
> > +		return __atomic_fetch_add(val, 1, __ATOMIC_RELAXED);
> > +	else
> > +		return (*val)++;
> > +}
> 
> This is a bad pattern. None of the rest of DPDK does this.
> Either be thread safe or not.

[Anoob] Most protocol implementation would have a similar issue. I've tried to follow the approach taken in lib IPsec (please check lib/ipsec/ipsec_sqn.h). From the discussion we had on v3, I've tried to make it compile time constant to remove any conditional checks in datapath.

If you still think, this is an issue, I could drop this patch for now and re-introduce it later once we have test applications that can work with traffic. Please share your thoughts.