From: Tyler Retzlaff <roretzla@linux.microsoft.com>
To: "Morten Brørup" <mb@smartsharesystems.com>
Cc: thomas@monjalon.net, dev@dpdk.org,
Ajit Khaparde <ajit.khaparde@broadcom.com>,
Andrew Boyer <andrew.boyer@amd.com>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
Bruce Richardson <bruce.richardson@intel.com>,
Chenbo Xia <chenbox@nvidia.com>,
Chengwen Feng <fengchengwen@huawei.com>,
Dariusz Sosnowski <dsosnowski@nvidia.com>,
David Christensen <drc@linux.vnet.ibm.com>,
Hyong Youb Kim <hyonkim@cisco.com>,
Jerin Jacob <jerinj@marvell.com>, Jie Hai <haijie1@huawei.com>,
Jingjing Wu <jingjing.wu@intel.com>,
John Daley <johndale@cisco.com>,
Kevin Laatz <kevin.laatz@intel.com>,
Kiran Kumar K <kirankumark@marvell.com>,
Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>,
Maciej Czekaj <mczekaj@marvell.com>,
Matan Azrad <matan@nvidia.com>,
Maxime Coquelin <maxime.coquelin@redhat.com>,
Nithin Dabilpuram <ndabilpuram@marvell.com>,
Ori Kam <orika@nvidia.com>, Ruifeng Wang <ruifeng.wang@arm.com>,
Satha Rao <skoteshwar@marvell.com>,
Somnath Kotur <somnath.kotur@broadcom.com>,
Suanming Mou <suanmingm@nvidia.com>,
Sunil Kumar Kori <skori@marvell.com>,
Viacheslav Ovsiienko <viacheslavo@nvidia.com>,
Yisen Zhuang <yisen.zhuang@huawei.com>,
Yuying Zhang <Yuying.Zhang@intel.com>
Subject: Re: [PATCH v6 01/23] mbuf: add accessors for rearm and Rx descriptor fields
Date: Wed, 28 Feb 2024 08:20:34 -0800 [thread overview]
Message-ID: <20240228162034.GA27142@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35E9F27F@smartserver.smartshare.dk>
On Wed, Feb 28, 2024 at 09:28:22AM +0100, Morten Brørup wrote:
> +To: Thomas, previously joined the discussion
>
> > From: Tyler Retzlaff [mailto:roretzla@linux.microsoft.com]
> > Sent: Tuesday, 27 February 2024 18.17
> >
> > On Tue, Feb 27, 2024 at 10:10:03AM +0100, Morten Brørup wrote:
> > > > From: Tyler Retzlaff [mailto:roretzla@linux.microsoft.com]
> > > > Sent: Tuesday, 27 February 2024 06.41
> > > >
> > > > RTE_MARKER typedefs are a GCC extension unsupported by MSVC. Provide
> > > > inline functions to access compatible type pointer to rearm_data
> > > > and rx_descriptor_fields1 which will allow direct references on the
> > > > rte marker fields to be removed.
> > > >
> > > > Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> > > > ---
> > > > lib/mbuf/rte_mbuf.h | 13 +++++++++++++
> > > > lib/mbuf/rte_mbuf_core.h | 11 ++++++++++-
> > > > 2 files changed, 23 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h
> > > > index 286b32b..aa7495b 100644
> > > > --- a/lib/mbuf/rte_mbuf.h
> > > > +++ b/lib/mbuf/rte_mbuf.h
> > > > @@ -132,6 +132,19 @@
> > > > #endif
> > > > }
> > > >
> > > > +static inline
> > > > +uint64_t *
> > > > +rte_mbuf_rearm_data(struct rte_mbuf *m)
> > > > +{
> > > > + return (uint64_t *)&m->data_off;
> > > > +}
> > >
> > > Consider returning (void *) instead of (uint64_t *).
> > > Just a suggestion; I don't know which is better.
> >
> > if you mean just the cast i don't think it matters.
>
> No, I meant the return type.
> The type is opaque; only its size is fixed at 8 byte.
> Maybe uint64_t * is the best type, after all.
ah, in many places the drivers want the uint64_t * keeping it here allows
for some of the casts (and potential for mistakes) to be discarded. if i
recall in some places they do math on the returned pointer.
>
> > arguably it could go
> > void * first but we're already aliasing through a different type. this
> > is one argument in favor of the union.
>
> The zero-size markers (rearm_data and rx_descriptor_fields1) were intended to be used like unions, which the drivers effectively do.
> Previous C standards didn't allow anonymous structures, so using union+struct in pre-C11 DPDK would clutter the code with subfield names. But now that we moved on to C11, we don't have this problem anymore.
>
> IMHO, replacing the zero-size markers - which are directly visible in the structure's source code - with access functions located in some other header file degrades source code readability.
>
> I am in favor of union+struct in the mbuf structure over access functions. I think the explicit grouping of the fields improves the readability of the mbuf structure, also compared to the zero-size markers.
it's unfortunate the zero-size markers could be accessed slightly
differently than the anonymous unions necessitating code referencing
them to be changed.
Thomas and i discussed rearm_data and rx_descriptor_fields1 at length
and it was understood why i had to add new field names if using the union
approach there was an expressed preference for accessors.
one possibly important detail that came out of our conversation was that
rearm_data rx_descriptor_fields1 are (I think) supposed to be internal
and that being the case means updading the dpdk drivers means i updated
*all* consumers i.e. i can break the api and adapt in the same commit if
they are truly internal because no application should be accessing the
fields.
one approach i've enjoyed some success with is to present semi-opaque
structures where the internal fields are by convention discouraged in
their use but doing this requires duplicating parts of the whole to e.g.
give the drivers the view of the struct they need and is an increased
burden for maintainers. again this relies on the fields actually being
internal only.
both approaches have been put up in this series now, just looking for
folks to look at the two and push for one or the other.
thanks!
next prev parent reply other threads:[~2024-02-28 16:20 UTC|newest]
Thread overview: 171+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 23:26 [PATCH] replace GCC marker extension with C11 anonymous unions Tyler Retzlaff
2024-01-30 23:26 ` [PATCH] mbuf: " Tyler Retzlaff
2024-01-31 9:18 ` Morten Brørup
2024-01-31 21:09 ` Tyler Retzlaff
2024-01-31 22:39 ` Morten Brørup
2024-01-31 13:49 ` Bruce Richardson
2024-01-31 20:45 ` Tyler Retzlaff
2024-01-31 22:55 ` Morten Brørup
2024-02-13 6:45 ` [PATCH v2] RFC: " Tyler Retzlaff
2024-02-13 6:45 ` [PATCH v2] mbuf: " Tyler Retzlaff
2024-02-13 16:58 ` Morten Brørup
2024-02-13 18:48 ` Tyler Retzlaff
2024-02-13 19:27 ` Morten Brørup
2024-02-13 20:00 ` Tyler Retzlaff
2024-02-13 8:57 ` [PATCH v2] RFC: " Bruce Richardson
2024-02-13 17:09 ` Morten Brørup
2024-02-13 23:33 ` [PATCH v3] RFC deprecate RTE_MARKER in struct rte_mbuf Tyler Retzlaff
2024-02-13 23:33 ` [PATCH v3] mbuf: deprecate GCC marker in rte mbuf struct Tyler Retzlaff
2024-02-14 10:46 ` Morten Brørup
2024-02-14 20:16 ` Tyler Retzlaff
2024-02-14 10:49 ` [PATCH v3] RFC deprecate RTE_MARKER in struct rte_mbuf Morten Brørup
2024-02-26 1:18 ` Stephen Hemminger
2024-02-15 6:21 ` [PATCH v4 00/18] stop using zero sized marker fields Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 01/18] mbuf: deprecate GCC marker in rte mbuf struct Tyler Retzlaff
2024-02-18 2:28 ` fengchengwen
2024-02-18 12:39 ` Thomas Monjalon
2024-02-18 13:07 ` Morten Brørup
2024-02-18 15:22 ` Thomas Monjalon
2024-02-18 16:20 ` Morten Brørup
2024-02-20 17:24 ` Tyler Retzlaff
2024-02-20 17:20 ` Tyler Retzlaff
2024-02-20 17:53 ` Thomas Monjalon
2024-02-20 19:16 ` Thomas Monjalon
2024-02-20 19:37 ` Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 02/18] mbuf: stop using zero sized marker fields Tyler Retzlaff
2024-02-18 2:38 ` fengchengwen
2024-02-15 6:21 ` [PATCH v4 03/18] net/i40e: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 04/18] net/iavf: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 05/18] net/ice: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 06/18] net/ixgbe: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 07/18] net/mlx5: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 08/18] net/sfc: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 09/18] net/bnxt: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 10/18] net/enic: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 11/18] net/fm10k: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 12/18] net/hns3: " Tyler Retzlaff
2024-02-18 3:00 ` fengchengwen
2024-02-15 6:21 ` [PATCH v4 13/18] net/ionic: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 14/18] net/thunderx: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 15/18] net/virtio: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 16/18] net/cnxk: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 17/18] common/idpf: " Tyler Retzlaff
2024-02-15 6:21 ` [PATCH v4 18/18] examples/dma: " Tyler Retzlaff
2024-02-15 9:37 ` [PATCH v4 00/18] " Morten Brørup
2024-02-24 8:21 ` [PATCH v5 00/22] stop using RTE_MARKER extensions Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 01/22] eal: provide macro to expand marker extensions Tyler Retzlaff
2024-02-24 10:51 ` Thomas Monjalon
2024-02-24 11:18 ` Thomas Monjalon
2024-02-24 8:21 ` [PATCH v5 02/22] mbuf: expand rte markers empty when building with MSVC Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 03/22] security: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 04/22] cryptodev: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 05/22] mbuf: stop using mbuf cacheline marker fields Tyler Retzlaff
2024-02-24 10:58 ` Thomas Monjalon
2024-02-26 18:20 ` Stephen Hemminger
2024-02-24 8:21 ` [PATCH v5 06/22] mbuf: add mbuf descriptor accessors Tyler Retzlaff
2024-02-24 11:01 ` Thomas Monjalon
2024-02-24 8:21 ` [PATCH v5 07/22] common/idpf: use " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 08/22] net/bnxt: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 09/22] net/cnxk: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 10/22] net/enic: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 11/22] net/fm10k: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 12/22] net/hns3: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 13/22] net/i40e: " Tyler Retzlaff
2024-02-24 8:21 ` [PATCH v5 14/22] net/iavf: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 15/22] net/ice: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 16/22] net/ionic: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 17/22] net/ixgbe: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 18/22] net/mlx5: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 19/22] net/octeon_ep: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 20/22] net/sfc: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 21/22] net/thunderx: " Tyler Retzlaff
2024-02-24 8:22 ` [PATCH v5 22/22] net/virtio: " Tyler Retzlaff
2024-02-24 10:42 ` [PATCH v5 00/22] stop using RTE_MARKER extensions Morten Brørup
2024-02-24 11:13 ` Thomas Monjalon
2024-02-24 11:23 ` Morten Brørup
2024-02-27 5:41 ` [PATCH v6 00/23] stop and remove RTE_MARKER typedefs Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 01/23] mbuf: add accessors for rearm and Rx descriptor fields Tyler Retzlaff
2024-02-27 9:10 ` Morten Brørup
2024-02-27 17:17 ` Tyler Retzlaff
2024-02-28 8:28 ` Morten Brørup
2024-02-28 16:20 ` Tyler Retzlaff [this message]
2024-02-27 5:41 ` [PATCH v6 02/23] mbuf: consolidate driver asserts for mbuf struct Tyler Retzlaff
2024-02-27 10:02 ` Konstantin Ananyev
2024-03-14 16:51 ` Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 03/23] common/idpf: use mbuf descriptor accessors Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 04/23] net/bnxt: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 05/23] net/cnxk: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 06/23] net/enic: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 07/23] net/fm10k: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 08/23] net/hns3: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 09/23] net/i40e: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 10/23] net/iavf: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 11/23] net/ice: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 12/23] net/ionic: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 13/23] net/ixgbe: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 14/23] net/mlx5: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 15/23] net/octeon_ep: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 16/23] net/sfc: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 17/23] net/thunderx: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 18/23] net/virtio: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 19/23] examples/dma: use mbuf descriptor accessor Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 20/23] mbuf: remove and stop using rte marker fields Tyler Retzlaff
2024-02-27 9:15 ` Morten Brørup
2024-02-27 10:03 ` Konstantin Ananyev
2024-02-27 15:18 ` David Marchand
2024-02-27 16:04 ` Morten Brørup
2024-02-27 17:23 ` Tyler Retzlaff
2024-02-28 10:42 ` David Marchand
2024-02-28 14:03 ` Dodji Seketeli
2024-02-28 14:43 ` David Marchand
2024-02-29 14:50 ` Dodji Seketeli
2024-02-28 14:18 ` David Marchand
2024-02-28 15:01 ` Morten Brørup
2024-02-28 15:33 ` David Marchand
2024-02-28 17:20 ` Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 21/23] security: remove " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 22/23] cryptodev: " Tyler Retzlaff
2024-02-27 5:41 ` [PATCH v6 23/23] devtools: forbid new use of rte marker typedefs Tyler Retzlaff
2024-03-20 22:01 ` [PATCH v7 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-03-20 22:01 ` [PATCH v7 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-03-26 10:16 ` Morten Brørup
2024-03-27 18:14 ` Tyler Retzlaff
2024-03-27 19:45 ` Morten Brørup
2024-03-20 22:01 ` [PATCH v7 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-03-21 10:32 ` Bruce Richardson
2024-03-21 15:31 ` Tyler Retzlaff
2024-03-21 16:19 ` Morten Brørup
2024-03-26 11:12 ` Morten Brørup
2024-03-20 22:01 ` [PATCH v7 3/4] security: " Tyler Retzlaff
2024-03-26 10:28 ` Morten Brørup
2024-03-27 19:59 ` Tyler Retzlaff
2024-03-20 22:01 ` [PATCH v7 4/4] cryptodev: " Tyler Retzlaff
2024-03-26 10:31 ` Morten Brørup
2024-03-27 19:56 ` [PATCH v8 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-03-27 19:56 ` [PATCH v8 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-03-27 19:56 ` [PATCH v8 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-03-27 19:56 ` [PATCH v8 3/4] security: " Tyler Retzlaff
2024-03-27 19:56 ` [PATCH v8 4/4] cryptodev: " Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-02 20:45 ` Stephen Hemminger
2024-04-02 20:51 ` Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 3/4] security: " Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 4/4] cryptodev: " Tyler Retzlaff
2024-04-03 17:53 ` [PATCH v10 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-03 17:53 ` [PATCH v10 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-03 21:49 ` Stephen Hemminger
2024-04-03 17:53 ` [PATCH v10 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-03 19:32 ` Morten Brørup
2024-04-03 22:45 ` Tyler Retzlaff
2024-04-03 21:49 ` Stephen Hemminger
2024-04-03 17:53 ` [PATCH v10 3/4] security: " Tyler Retzlaff
2024-04-03 21:50 ` Stephen Hemminger
2024-04-03 17:53 ` [PATCH v10 4/4] cryptodev: " Tyler Retzlaff
2024-04-03 21:50 ` Stephen Hemminger
2024-04-04 17:51 ` [PATCH v11 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-04 17:51 ` [PATCH v11 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-04 17:51 ` [PATCH v11 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-04 17:51 ` [PATCH v11 3/4] security: " Tyler Retzlaff
2024-04-04 17:51 ` [PATCH v11 4/4] cryptodev: " Tyler Retzlaff
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