From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Eads, Gage" <gage.eads@intel.com>
Subject: Re: [PATCH v2 1/1] eal: add 128-bit cmpxchg (x86-64 only)
Date: Mon, 4 Mar 2019 20:47:04 +0000
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Cc: "olivier.matz@6wind.com" <olivier.matz@6wind.com>,
 "arybchenko@solarflare.com" <arybchenko@solarflare.com>, "Richardson, Bruce"
 <bruce.richardson@intel.com>, "Ananyev, Konstantin"
 <konstantin.ananyev@intel.com>, "Gavin Hu (Arm Technology China)"
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 "hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>, nd <nd@arm.com>
To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>, "dev@dpdk.org"
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[snip]

> > +/**
> > + * An atomic compare and set function used by the mutex functions.
> > + * (Atomically) Equivalent to:
> > + *   if (*dst =3D=3D exp)
> Should be, "if (*dst =3D=3D *exp)"
>=20
> > + *     *dst =3D src
> Should be "*dst =3D *src"
>=20

Good catches, will fix both.

> > + *   else
> > + *     *exp =3D *dst
> > + *
> > + * @note The success and failure arguments must be one of the
> > +__ATOMIC_* values
> > + * defined in the C++11 standard. For details on their behavior,
> > +refer to the
> > + * standard.
> > + *
> > + * @param dst
> > + *   The destination into which the value will be written.
> > + * @param exp
> > + *   Pointer to the expected value. If the operation fails, this memor=
y is
> > + *   updated with the actual value.
> > + * @param src
> > + *   Pointer to the new value.
> > + * @param weak
> > + *   A value of true allows the comparison to spuriously fail and allo=
ws the
> > + *   'exp' update to occur non-atomically (i.e. a torn read may occur)=
.
> > + *   Implementations may ignore this argument and only implement the
> strong
> > + *   variant.
> > + * @param success
> > + *   If successful, the operation's memory behavior conforms to this (=
or a
> > + *   stronger) model.
> > + * @param failure
> > + *   If unsuccessful, the operation's memory behavior conforms to this=
 (or a
> > + *   stronger) model. This argument cannot be __ATOMIC_RELEASE,
> > + *   __ATOMIC_ACQ_REL, or a stronger model than success.
> > + * @return
> > + *   Non-zero on success; 0 on failure.
> > + */
> > +static inline int __rte_experimental
> > +rte_atomic128_cmpxchg(rte_int128_t *dst,
> Name could be more neutral. May be rte_atomic128_compare/cmp_exchange?
>=20
> > +		      rte_int128_t *exp,
> > +		      const rte_int128_t *src,
> > +		      unsigned int weak,
> > +		      int success,
> > +		      int failure);
> > +#endif
> > +
> >  #endif /* _RTE_ATOMIC_H_ */
> > --
> > 2.13.6
>=20

Sure -- I'll rename it rte_atomic128_cmp_exchange in the next version.

> Few minor comments.
> I have not reviewed the x86 implementation.
> Otherwise,
> Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Thanks,
Gage