From: Neil Horman <nhorman@tuxdriver.com> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com> Cc: Bruce Richardson <bruce.richardson@intel.com>, "dev@dpdk.org" <dev@dpdk.org>, Thomas Monjalon <thomas@monjalon.net> Subject: Re: [dpdk-dev] [EXT] [RFC PATCH 0/2] introduce __rte_internal tag Date: Thu, 6 Jun 2019 09:35:03 -0400 Message-ID: <20190606133503.GB29521@hmswarspite.think-freely.org> (raw) In-Reply-To: <BYAPR18MB242407B0A2A21E187843917FC8170@BYAPR18MB2424.namprd18.prod.outlook.com> On Thu, Jun 06, 2019 at 12:04:57PM +0000, Jerin Jacob Kollanukkaran wrote: > > -----Original Message----- > > From: Neil Horman <nhorman@tuxdriver.com> > > Sent: Thursday, June 6, 2019 5:04 PM > > To: Jerin Jacob Kollanukkaran <jerinj@marvell.com> > > Cc: Bruce Richardson <bruce.richardson@intel.com>; dev@dpdk.org; > > Thomas Monjalon <thomas@monjalon.net> > > Subject: Re: [EXT] [RFC PATCH 0/2] introduce __rte_internal tag > > > > On Thu, Jun 06, 2019 at 09:44:52AM +0000, Jerin Jacob Kollanukkaran wrote: > > > > -----Original Message----- > > > > From: Neil Horman <nhorman@tuxdriver.com> > > > > Sent: Wednesday, June 5, 2019 11:41 PM > > > > To: Bruce Richardson <bruce.richardson@intel.com> > > > > Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; dev@dpdk.org; > > > > Thomas Monjalon <thomas@monjalon.net> > > > > Subject: Re: [EXT] [RFC PATCH 0/2] introduce __rte_internal tag > > > > > > > > On Wed, Jun 05, 2019 at 05:45:41PM +0100, Bruce Richardson wrote: > > > > > On Wed, Jun 05, 2019 at 04:24:09PM +0000, Jerin Jacob > > > > > Kollanukkaran > > > > wrote: > > > > > > > -----Original Message----- > > > > > > > From: Neil Horman <nhorman@tuxdriver.com> > > > > > > > Sent: Sunday, May 26, 2019 12:14 AM > > > > > > > To: dev@dpdk.org > > > > > > > Cc: Neil Horman <nhorman@tuxdriver.com>; Jerin Jacob > > > > > > > Kollanukkaran <jerinj@marvell.com>; Bruce Richardson > > > > > > > <bruce.richardson@intel.com>; Thomas Monjalon > > > > > > > <thomas@monjalon.net> > > > > > > > Subject: [EXT] [RFC PATCH 0/2] introduce __rte_internal tag > > > > > > > > > > > > > > Hey- > > > > > > > Based on our recent conversations regarding the use of > > > > > > > symbols only meant for internal dpdk consumption (between dpdk > > > > > > > libraries), this is an idea that I've come up with that I'd > > > > > > > like to get some feedback on > > > > > > > > > > > > > > Summary: > > > > > > > 1) We have symbols in the DPDK that are meant to be used > > > > > > > between DPDK libraries, but not by applications linking to > > > > > > > them > > > > > > > 2) We would like to document those symbols in the code, so as > > > > > > > to note them clearly as for being meant for internal use only > > > > > > > 3) Linker symbol visibility is a very coarse grained tool, and > > > > > > > so there is no good way in a single library to mark items as > > > > > > > being meant for use only by other DPDK libraries, at least not > > > > > > > without some extensive runtime checking > > > > > > > > > > > > > > > > > > > > > Proposal: > > > > > > > I'm proposing that we introduce the __rte_internal tag. From > > > > > > > a coding standpoint it works a great deal like the > > > > > > > __rte_experimental tag in that it expempts the tagged symbol > > > > > > > from ABI constraints (as the only users should be represented > > > > > > > in the DPDK build environment). Additionally, the > > > > > > > __rte_internal macro resolves differently based on the > > > > > > > definition of the BUILDING_RTE_SDK flag (working under the > > > > > > > assumption that said flag should only ever be set if we are > > > > > > > actually building DPDK libraries which will make use of > > > > > > > internal calls). If the BUILDING_RTE_SDK flag is set > > > > > > > __rte_internal resolves to __attribute__((section > > > > > > > "text.internal)), placing it in a special text section which > > > > > > > is then used to validate that the the symbol appears in the > > > > > > > INTERNAL section of the corresponding library version map). > > > > > > > If BUILDING_RTE_SDK is not set, then __rte_internal resolves > > > > > > > to > > > > __attribute__((error("..."))), which causes any caller of the tagged > > > > function to throw an error at compile time, indicating that the > > > > symbol is not available for external use. > > > > > > > > > > > > > > This isn't a perfect solution, as applications can still hack > > > > > > > around it of course, > > > > > > > > > > > > I think, one way to, avoid, hack around could be to, > > > > > > > > > > > > 1) at config stage, create a random number for the build > > > > > > 2) introduce RTE_CALL_INTERNAL macro for calling internal > > > > > > function, compare the generated random number for allowing the > > > > > > calls to make within the library. i.e leverage the fact that > > > > > > external library would never know the random number generated > > > > > > for the DPDK build > > > > and internal driver code does. > > > > > > > > > > > Do we really need to care about this. If have some determined > > > > > enough to hack around our limitations, then they surely know that > > > > > they have an unsupported configuration. We just need to protect > > > > > against inadvertent use of internals, IMHO. > > > > > > > > > I agree, I too had thought about doing some sort of internal runtime > > > > checking to match internal only symbols, such that they were only > > > > accessable by internally approved users, but it started to feel like a great > > deal of overhead. > > > > Its a good idea for a general mechanism I think, but I believe the > > > > value here is more to internally document which apis we want to mark > > > > as being for internal use only, and create a lightweight roadblock > > > > at build time to catch users inadvertently using them. Determined > > > > users will get around anything, and theres not much we can do to stop > > them. > > > > > > I agree too. IMHO, Simply having following items would be enough > > > > > > 1) Avoid exposing the internal function prototype through public > > > header files > > > 2) Add @internal to API documentation > > > 3) Just decide the name space for internal API for tooling(i.e not > > > start with rte_ or so) Using objdump scheme to detect internal functions > > requires the the library to build prior to run the checkpatch. > > > > > > > No, I'm not comfortable with that approach, and I've stated why: > > 1) Not exposing the functions via header files is a fine start > > > > 2) Adding internal documentation is also fine, but does nothing to correlate > > the code implementing those functions to the documentation. Its valuable > > to have a tag on a function identifying it as internal only. > > > > 3) Using naming conventions to separate internal only from non-internal > > functions is a vague approach, requiring future developers to be cogniscent > > of the convention and make the appropriate naming choices. It also implicitly > > restricts the abliity for future developers to make naming changes in conflict > > with that convention > > Enforcing the naming convention can be achieved through tooling as well. > Sure, but why enforce any function naming at all, when you don't have to. > > > > 4) Adding a tag like __rte_internal creates an interlock whereby, not only are > > internal functions excused from ABI constraints, but forces developers to > > intentionally mark their internal functions as being internal in the code, which > > is beneficial to clarlity of understanding during the development process. > > No issues in adding __rte_internal. But, I am against current implementaion, > Ie. adding objdump dependency That dependency already exists for the __rte_external flag > to checkpatch i.e developer has to build the library first so that checkpatch can > can know, Is it belongs to internal section or not? > What developer is running checkpatch/posting patches without first building their changes? > > > > 5) Adding a tag like __rte_internal is explicit, and allows developers to use a > > single header file instead of multiple header files if they so choose > > > > We went through this with experimental symbols as well[1], and it just > > makes more sense to me to clearly document in the code what constitutes > > an internal symbol rather than relying on naming conventions and hoping > > that developers read the documentation before exporting a symbol > > publically. > > > > > > [1] https://mails.dpdk.org/archives/dev/2017-December/083828.html > > > > > > > > If we really wanted to go down that road, we could use a mechainsm > > > > simmilar to the EXPORT_SYMBOL / EXPORT_SYMBOL_GPL infrastructure > > > > that the kernel uses, but that would required building our own > > > > custom linker script, which seems like overkill here. > > > > > > > > Best > > > > Neil > > > > > > > > > /Bruce > > > > > > > > >
next prev parent reply index Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-25 18:43 [dpdk-dev] " Neil Horman 2019-05-25 18:43 ` [dpdk-dev] [RFC PATCH 1/2] Add __rte_internal tag for functions and version target Neil Horman 2019-06-05 16:14 ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran 2019-05-25 18:43 ` [dpdk-dev] [RFC PATCH 2/2] Convert dpaa driver to tag internal-only symbols appropriately Neil Horman 2019-06-05 16:24 ` [dpdk-dev] [EXT] [RFC PATCH 0/2] introduce __rte_internal tag Jerin Jacob Kollanukkaran 2019-06-05 16:45 ` Bruce Richardson 2019-06-05 18:11 ` Neil Horman 2019-06-06 9:44 ` Jerin Jacob Kollanukkaran 2019-06-06 11:34 ` Neil Horman 2019-06-06 12:04 ` Jerin Jacob Kollanukkaran 2019-06-06 13:18 ` Wiles, Keith 2019-06-06 13:43 ` Neil Horman 2019-06-06 13:53 ` Wiles, Keith 2019-06-06 14:46 ` Neil Horman 2019-06-06 13:35 ` Neil Horman [this message] 2019-06-06 14:02 ` Jerin Jacob Kollanukkaran 2019-06-06 15:03 ` Neil Horman 2019-06-06 15:14 ` Jerin Jacob Kollanukkaran 2019-06-06 15:26 ` Neil Horman 2019-06-06 16:23 ` Jerin Jacob Kollanukkaran 2019-06-06 16:55 ` Neil Horman 2019-06-07 9:41 ` Jerin Jacob Kollanukkaran 2019-06-07 10:35 ` Neil Horman 2019-06-07 15:42 ` Ray Kinsella 2019-06-07 18:21 ` Wiles, Keith 2020-01-09 15:49 ` Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 0/9] dpdk: " Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 1/9] Add __rte_internal tag for functions and version target Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 2/9] Exempt INTERNAL symbols from checking Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 3/9] mark dpaa driver internal-only symbols with __rte_internal Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 4/9] fslmc: identify internal only functions and tag them as __rte_internal Neil Horman 2019-06-12 20:38 ` [dpdk-dev] [PATCH v1 5/9] dpaa2: Adjust dpaa2 driver to mark internal symbols with __rte_internal Neil Horman 2019-06-12 20:39 ` [dpdk-dev] [PATCH v1 6/9] dpaax: mark internal functions " Neil Horman 2019-06-12 20:39 ` [dpdk-dev] [PATCH v1 7/9] cpt: " Neil Horman 2019-06-17 5:27 ` [dpdk-dev] [EXT] " Anoob Joseph 2019-06-12 20:39 ` [dpdk-dev] [PATCH v1 8/9] octeonx: " Neil Horman 2019-06-12 20:39 ` [dpdk-dev] [PATCH v1 9/9] dpaa2: " Neil Horman 2019-06-12 21:14 ` Aaron Conole 2019-06-13 10:24 ` Neil Horman 2019-06-13 7:53 ` [dpdk-dev] [PATCH v1 0/9] dpdk: introduce __rte_internal tag David Marchand 2019-06-13 10:30 ` Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 0/10] " Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 01/10] Add __rte_internal tag for functions and version target Neil Horman 2020-04-17 2:04 ` Wang, Haiyue 2020-04-17 2:38 ` Neil Horman 2020-04-17 4:40 ` Wang, Haiyue 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 02/10] meson: add BUILDING_RTE_SDK Neil Horman 2019-06-13 14:44 ` Bruce Richardson 2019-06-19 10:39 ` Neil Horman 2019-06-19 10:46 ` Bruce Richardson 2019-06-19 18:34 ` Neil Horman 2019-06-20 10:20 ` Bruce Richardson 2019-06-20 10:21 ` Bruce Richardson 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 03/10] Exempt INTERNAL symbols from checking Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 04/10] mark dpaa driver internal-only symbols with __rte_internal Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 05/10] fslmc: identify internal only functions and tag them as __rte_internal Neil Horman 2019-06-17 7:30 ` Hemant Agrawal 2019-06-19 10:45 ` Neil Horman 2020-04-02 9:49 ` Hemant Agrawal 2020-04-02 11:30 ` Neil Horman 2020-04-02 15:44 ` Hemant Agrawal 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 06/10] dpaa2: Adjust dpaa2 driver to mark internal symbols with __rte_internal Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 07/10] dpaax: mark internal functions " Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 08/10] cpt: " Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 09/10] octeonx: " Neil Horman 2019-06-13 14:23 ` [dpdk-dev] [PATCH v2 10/10] dpaa2: " Neil Horman 2019-08-06 10:03 ` [dpdk-dev] [PATCH v2 0/10] dpdk: introduce __rte_internal tag Thomas Monjalon 2019-08-06 12:21 ` Neil Horman 2020-01-09 9:55 ` David Marchand 2020-01-09 11:46 ` Neil Horman 2020-01-09 11:53 ` David Marchand 2020-04-22 13:52 ` [dpdk-dev] [PATCH v3 0/1] " Haiyue Wang 2020-04-22 13:52 ` [dpdk-dev] [PATCH v3 1/1] eal: add internal ABI mark support Haiyue Wang 2020-04-22 14:13 ` David Marchand 2020-04-22 16:44 ` Wang, Haiyue 2020-04-22 16:37 ` [dpdk-dev] [PATCH v4 0/1] dpdk: introduce __rte_internal tag Haiyue Wang 2020-04-22 16:37 ` [dpdk-dev] [PATCH v4 1/1] eal: add internal ABI mark support Haiyue Wang 2020-04-23 3:19 ` [dpdk-dev] [PATCH v5 0/1] dpdk: introduce __rte_internal tag Haiyue Wang 2020-04-23 3:19 ` [dpdk-dev] [PATCH v5 1/1] eal: add internal ABI marking support Haiyue Wang 2020-04-24 14:52 ` David Marchand 2020-04-25 6:10 ` Wang, Haiyue 2020-04-25 14:21 ` David Marchand 2020-04-25 14:24 ` Thomas Monjalon 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 0/6] dpdk: introduce __rte_internal tag Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 1/6] eal: add internal ABI tag definition Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 2/6] build: enable internal API tag Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 3/6] mk: add internal tag check Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 4/6] devtools: ignore internal ABI check Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 5/6] devtools: exempt internal ABI checking Haiyue Wang 2020-04-25 6:04 ` [dpdk-dev] [PATCH v6 6/6] devtools: enforce internal tag at the beginning Haiyue Wang 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 0/6] dpdk: introduce __rte_internal tag Haiyue Wang 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 1/6] eal: add internal ABI tag definition Haiyue Wang 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 2/6] build: enable internal API tag Haiyue Wang 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 3/6] mk: add internal tag check Haiyue Wang 2020-04-25 14:34 ` David Marchand 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 4/6] devtools: ignore internal ABI check Haiyue Wang 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 5/6] devtools: exempt internal ABI checking Haiyue Wang 2020-04-25 14:34 ` David Marchand 2020-04-25 10:56 ` [dpdk-dev] [PATCH v7 6/6] devtools: enforce internal tag at the beginning Haiyue Wang 2020-04-25 14:39 ` [dpdk-dev] [PATCH v7 0/6] dpdk: introduce __rte_internal tag David Marchand 2020-04-25 16:34 ` Wang, Haiyue 2020-04-25 18:09 ` Wang, Haiyue 2020-04-29 8:22 ` David Marchand 2020-04-29 8:24 ` Wang, Haiyue
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