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* Re: [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers
@ 2019-05-22 13:12 Jerin Jacob Kollanukkaran
  2019-05-22 13:40 ` Neil Horman
  0 siblings, 1 reply; 14+ messages in thread
From: Jerin Jacob Kollanukkaran @ 2019-05-22 13:12 UTC (permalink / raw)
  To: Neil Horman; +Cc: dev, thomas, stable

> -----Original Message-----
> From: Neil Horman <nhorman@tuxdriver.com>
> Sent: Wednesday, May 22, 2019 6:16 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: dev@dpdk.org; thomas@monjalon.net; stable@dpdk.org
> Subject: Re: [EXT] Re: [dpdk-dev] [PATCH] devtools: skip the symbol check
> when map file under drivers
> 
> On Wed, May 22, 2019 at 03:05:54AM +0000, Jerin Jacob Kollanukkaran
> wrote:
> > > -----Original Message-----
> > > From: Neil Horman <nhorman@tuxdriver.com>
> > > Sent: Wednesday, May 22, 2019 1:57 AM
> > > To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> > > Cc: dev@dpdk.org; thomas@monjalon.net; stable@dpdk.org
> > > Subject: [EXT] Re: [dpdk-dev] [PATCH] devtools: skip the symbol
> > > check when map file under drivers
> > >
> > > On Wed, May 22, 2019 at 01:26:28AM +0530, jerinj@marvell.com wrote:
> > > > From: Jerin Jacob <jerinj@marvell.com>
> > > >
> > > > Drivers do not have ABI.
> > > > Skip the symbol check if map file under drivers directory.
> > > >
> > > > Fixes: 4bec48184e33 ("devtools: add checks for ABI symbol
> > > > addition")
> > > >
> > > > Cc: stable@dpdk.org
> > > > Cc: Neil Horman <nhorman@tuxdriver.com>
> > > >
> > > Sorry, but I'm not ok with this, because many of our DPDK PMDs have
> > > functions that get exported which are meant to be called by
> > > applications directly.  The
> >
> > OK. Just to update my knowledge, Should those API needs to go through
> > ABI/API depreciation process?
> >
> Yes, they definately should, they are API's just as any other in the core DPDK
> library.

OK


> 
> > Actually, I am concerned about the APIs, which is called between
> > drviers not the application. For example,
> > drivers/common/dpaax/rte_common_dpaax_version.map
> >
> > it is not interface to application rather it is for intra driver case.
> > I think, I can change my logic to Skip the symbols which NOT starting with
> rte_.
> > Agree?
> >
> No, Thats just one case, and if those calls are between drivers, so be it, but
> those still need to be stable, and we have other examples (like the bonding
> or dummy driver), which have additional APIs that are explicitly meant to be
> used by an application.

There is no disagreement on the API that exposed to application.
I am concerned with internal driver APIs. For example, I am getting following warning

ERROR: symbol otx2_mbox_alloc_msg_rsp is added in the DPDK_19.05 section, but is expected to be added in the EXPERIMENTAL section of the version map

This API suppose to be called only a octeontx2 network driver from octeontx2 common driver
i.e application should not expect any stability on intra driver functions or it does not meant to
be used by application.

Thomas,
Any thought on this?



> 
> > Context:
> > I am adding a new driver/common/octeontx2 directory and it has some
> > API which Needs to shared between drivers not to the application. For
> > me, it does not make sense to go through any ABI process in such case.
> >
> Why?  If you create an API thats reachable from another block of code (be it
> a driver or an application), you've created a dependency in which that API
> must remain stable, lest you risk breaking something.  If an end user writes
> an out-of-tree PMD which makes use of an an additional driver API, then you
> need to keep it stable or you will break them.
> 
> >
> > > dpaa2 driver is a good example, the cryptodev scheduler is another.
> > > Take a look at their version.map files to see what I mean.
> > >
> > > Unless we are willing to make drivers opaque objects that are only
> > > accessible from the [eth|crypto|etc]dev apis in the DPDK core, we
> > > have the potential for exported symbols, which means we have an ABI
> > > that has to be maintained, or at least recognized and reviewed for
> > > consistency
> > >
> > > Nacked-by: Neil Horman <nhorman@tuxdriver.com>
> > >
> > >
> > > > Signed-off-by: Jerin Jacob <jerinj@marvell.com>
> > > > ---
> > > >  devtools/check-symbol-change.sh | 8 ++++++++
> > > >  1 file changed, 8 insertions(+)
> > > >
> > > > diff --git a/devtools/check-symbol-change.sh
> > > > b/devtools/check-symbol-change.sh index c5434f3bb..444beddad
> > > > 100755
> > > > --- a/devtools/check-symbol-change.sh
> > > > +++ b/devtools/check-symbol-change.sh
> > > > @@ -93,6 +93,14 @@ check_for_rule_violations()
> > > >  		if [ "$ar" = "add" ]
> > > >  		then
> > > >
> > > > +			directory=`echo $mname | cut -d / -f 2`
> > > > +			if [ "$directory" = "drivers" ]
> > > > +			then
> > > > +				# Drivers do not have ABI. Skip further
> > > > +				# processing if the map file is under
> > > > +				# drivers directory
> > > > +				continue
> > > > +			fi
> > > >  			if [ "$secname" = "unknown" ]
> > > >  			then
> > > >  				# Just inform the user of this occurrence, but
> > > > --
> > > > 2.21.0
> > > >
> > > >
> >

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers
@ 2019-05-23 14:21 Jerin Jacob Kollanukkaran
  2019-05-23 17:57 ` Neil Horman
  0 siblings, 1 reply; 14+ messages in thread
From: Jerin Jacob Kollanukkaran @ 2019-05-23 14:21 UTC (permalink / raw)
  To: Neil Horman; +Cc: Bruce Richardson, dev, thomas, stable



> -----Original Message-----
> From: Neil Horman <nhorman@tuxdriver.com>
> Sent: Thursday, May 23, 2019 12:29 AM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: Bruce Richardson <bruce.richardson@intel.com>; dev@dpdk.org;
> thomas@monjalon.net; stable@dpdk.org
> Subject: Re: [EXT] Re: [dpdk-dev] Re: [PATCH] devtools: skip the symbol
> check when map file under drivers
> > > > > > IMO, The name prefix matters. The rte_* should denote it a
> > > > > > DPDK API and application suppose to use it.
> > > > > >
> > > > > It doesn't, its just a convention.  We have no documentation
> > > > > that indicates what the meaning of an rte_* prefix is
> > > > > specficially, above and beyond the fact thats how we name
> > > > > functions in the DPDK.  If you want to submit a patch to
> > > > > formalize the meaning of function prefixes, you're welcome too
> > > > > (though I won't support it, perhaps others will).  But even if
> > > > > you do, it doesn't address the underlying problem, which is that
> applications still have access to those symbols.
> > > > > Maintaining an ABI by assertion of prefix is really a lousy way
> > > > > to communicate what functions should be accessed by an
> > > > > application and which shouldn't.  If a function is exported, and
> > > > > included in the header file, people will try to use
> > > >
> > > > The current scheme in the driver/common is that, the header files
> > > > are NOT made It as public ie not installed make install.
> > > > The consumer driver includes that using relative path wrt DPDK
> > > > source
> > > directory.
> > > >
> > > Well, thats a step in the right direction.  I'd still like to see
> > > some enforcement to prevent the inadvertent use of those APIs though
> >
> > Yes header file  is  not exported. Not sure how a client can use those.
> > Other than doing some hacking.
> >
> Yes, self prototyping the exported functions would be a way around that.
> > >
> > > > Anyway I will add experimental section to make tool happy.
> > > >
> > > That really not the right solution.  Marking them as experimental is
> > > just papering over the problem, and suggests to users that they will
> > > one day be stable.
> >
> > That what my original concern.
> >
> > > What you want is to explicitly mark those symbols as internal only,
> > > so that any inadvertent use gets flagged.
> >
> > What is your final thought? I can assume the following for my patch
> > generation
> >
> > # No need to mark as experimental
> > # Add @internal to denote it is a internal function like followed some places
> in EAL.
> >
> These are both correct, yes.
> 
> In addition, I would like to see some mechanism that explicitly marks the
> function as exported only for the purposes of internal use.  I understand that
> yours is a case in which this is not expressly needed because you don't
> prototype those functions, but what I'd like to see is a macro in rte_compat.h
> somewhere like this:
> 
> #define INTERNAL_USE_ONLY do {static_assert(0, "Function is only available
> for internal DPDK usage");} while(0)
> 
> so that, in your exported header file (of which I'm sure you have one, even if
> it doesn't contain your private functions, you can do something like this:
> 
> #ifdef BUILDING_RTE_SDK
> void somefunc(int val);
> #else
> #define somefunc(x) INTERNAL_USE_ONLY
> #endif

I think, We have two cases
1) Internal functions are NOT available via  DPDK SDK exported header files
2) Internal functions are available via DPDK SDK exported header files

I think, you are trying to address case 2( as case 1 is not applicable in this context due lack of header file)
For case 2, IMO, the above scheme will not be enough as 
The consumer entity can simply add the exact C flags to skip that check in this case, -DBUILDING_RTE_SDK.
IMO, it would be correct remove private functions from public header files. No strong options on this.
 
> 
> This combination allows for 'internal' functions to be used (defining internal
> to mean access to functions only when building the DPDK SDK), while
> expressly breaking the build of any application which attempts to use these
> functions when not building the SDK (i.e. when building an application that
> expects to link to the DPDK after its built).  Again, I uderstand that in your
> case, it may be sufficient to just not prototype the functions you don't want
> used, but I think in the general case its important to have some mechanism
> to expressly prevent their usage outside the SDK
> 
> Best
> Neil
> 
> > >
> > > Neil
> > > >
> > > >
> >

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers
@ 2019-05-22 13:41 Jerin Jacob Kollanukkaran
  2019-05-22 14:11 ` Neil Horman
  0 siblings, 1 reply; 14+ messages in thread
From: Jerin Jacob Kollanukkaran @ 2019-05-22 13:41 UTC (permalink / raw)
  To: Neil Horman; +Cc: Bruce Richardson, dev, thomas, stable

> -----Original Message-----
> From: Neil Horman <nhorman@tuxdriver.com>
> Sent: Wednesday, May 22, 2019 6:43 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: Bruce Richardson <bruce.richardson@intel.com>; dev@dpdk.org;
> thomas@monjalon.net; stable@dpdk.org
> Subject: [EXT] Re: [dpdk-dev] Re: [PATCH] devtools: skip the symbol check
> when map file under drivers
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Wed, May 22, 2019 at 11:54:13AM +0000, Jerin Jacob Kollanukkaran
> wrote:
> > > -----Original Message-----
> > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > Sent: Wednesday, May 22, 2019 4:21 PM
> > > To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> > > Cc: Neil Horman <nhorman@tuxdriver.com>; dev@dpdk.org;
> > > thomas@monjalon.net; stable@dpdk.org
> > > Subject: Re: [dpdk-dev] [EXT] Re: [PATCH] devtools: skip the symbol
> > > check when map file under drivers
> > >
> > > > > Sorry, but I'm not ok with this, because many of our DPDK PMDs
> > > > > have functions that get exported which are meant to be called by
> > > > > applications directly.  The
> > > >
> > > > OK. Just to update my knowledge, Should those API needs to go
> > > > through ABI/API depreciation process?
> > > >
> > > > Actually, I am concerned about the APIs, which is called between
> > > > drviers not the application. For example,
> > > > drivers/common/dpaax/rte_common_dpaax_version.map
> > > >
> > > > it is not interface to application rather it is for intra driver case.
> > > > I think, I can change my logic to Skip the symbols which NOT
> > > > starting with
> > > rte_.
> > > > Agree?
> > > >
> > > > Context:
> > > > I am adding a new driver/common/octeontx2 directory and it has
> > > > some API which Needs to shared between drivers not to the
> > > > application. For me, it does not make sense to go through any ABI
> process in such case.
> > > >
> > > >
> > > Maybe not, but other drivers will have APIs designed for apps to
> > > call directly - some NIC drivers have them, and I suspect that
> > > rawdev drivers will need them a lot. Therefore, it's best to have
> > > the drivers directory scanned by our tooling.
> >
> > Agreed. But all of those API  which called directly called from
> > application is starts with rte_ symbol. How about skipping the symbols
> > which is NOT start with rte_*
> > example:
> > drivers/common/octeontx/rte_common_octeontx_version.map
> > drivers/common/dpaax/rte_common_dpaax_version.map
> >
> 
> No, that won't work.  If you export a function, it doesn't matter if its named
> rte_* or not.  Its accessible from any library/application that cares to call it,

IMO, The name prefix matters. The rte_* should denote it a DPDK API and application
suppose to use it.

I don't think, giving experimental status to intra driver API helps anyone, neither driver nor
application.

If you think strongly that experimental needs to be added for intra driver APIs then I can add that.
 

> and so you have a responsibility to keep it stable for those users.
> 
> Currently the way we have around that is the use of the __rte_experimental
> tag.
> Adding that tag to an exported function marks it as being unstable, and while
> you can use it, it will generate a build time warning about its use, unless you
> define ALLOW_EXPERIMENTAL_API.  You could use that, understanding that
> in-tree drivers could use it safely, as you should always be keeping the API in
> sync with its users, but thats not quite what you want I don't think.
> 
> Another solution (allbeit a slightly risky one), would be to bifurcate your
> header files into a public and private version, with the private version
> prototyping your driver-only functions properly, and the public version
> aliasing them such that they generate a build time error indicating those
> functions aren't available for public use (you can use the gcc static_assert
> macro I believe).  Users could circumvent it by pulling the private header out
> of the build, or just prototyping the functions themselves, but at that point a
> user is asking for trouble anyway
> 
> Neil

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers
@ 2019-05-22 11:54 Jerin Jacob Kollanukkaran
  2019-05-22 13:13 ` Neil Horman
  0 siblings, 1 reply; 14+ messages in thread
From: Jerin Jacob Kollanukkaran @ 2019-05-22 11:54 UTC (permalink / raw)
  To: Bruce Richardson; +Cc: Neil Horman, dev, thomas, stable

> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Wednesday, May 22, 2019 4:21 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> Cc: Neil Horman <nhorman@tuxdriver.com>; dev@dpdk.org;
> thomas@monjalon.net; stable@dpdk.org
> Subject: Re: [dpdk-dev] [EXT] Re: [PATCH] devtools: skip the symbol check
> when map file under drivers
> 
> > > Sorry, but I'm not ok with this, because many of our DPDK PMDs have
> > > functions that get exported which are meant to be called by
> > > applications directly.  The
> >
> > OK. Just to update my knowledge, Should those API needs to go through
> > ABI/API depreciation process?
> >
> > Actually, I am concerned about the APIs, which is called between
> > drviers not the application. For example,
> > drivers/common/dpaax/rte_common_dpaax_version.map
> >
> > it is not interface to application rather it is for intra driver case.
> > I think, I can change my logic to Skip the symbols which NOT starting with
> rte_.
> > Agree?
> >
> > Context:
> > I am adding a new driver/common/octeontx2 directory and it has some
> > API which Needs to shared between drivers not to the application. For
> > me, it does not make sense to go through any ABI process in such case.
> >
> >
> Maybe not, but other drivers will have APIs designed for apps to call directly -
> some NIC drivers have them, and I suspect that rawdev drivers will need
> them a lot. Therefore, it's best to have the drivers directory scanned by our
> tooling.

Agreed. But all of those API  which called directly called from application
is starts with rte_ symbol. How about skipping the symbols which is NOT start with rte_*
example:
drivers/common/octeontx/rte_common_octeontx_version.map
drivers/common/dpaax/rte_common_dpaax_version.map


^ permalink raw reply	[flat|nested] 14+ messages in thread
* [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers
@ 2019-05-21 19:56 jerinj
  2019-05-21 20:27 ` Neil Horman
  0 siblings, 1 reply; 14+ messages in thread
From: jerinj @ 2019-05-21 19:56 UTC (permalink / raw)
  To: Neil Horman; +Cc: dev, thomas, Jerin Jacob, stable

From: Jerin Jacob <jerinj@marvell.com>

Drivers do not have ABI.
Skip the symbol check if map file under drivers directory.

Fixes: 4bec48184e33 ("devtools: add checks for ABI symbol addition")

Cc: stable@dpdk.org
Cc: Neil Horman <nhorman@tuxdriver.com>

Signed-off-by: Jerin Jacob <jerinj@marvell.com>
---
 devtools/check-symbol-change.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/devtools/check-symbol-change.sh b/devtools/check-symbol-change.sh
index c5434f3bb..444beddad 100755
--- a/devtools/check-symbol-change.sh
+++ b/devtools/check-symbol-change.sh
@@ -93,6 +93,14 @@ check_for_rule_violations()
 		if [ "$ar" = "add" ]
 		then
 
+			directory=`echo $mname | cut -d / -f 2`
+			if [ "$directory" = "drivers" ]
+			then
+				# Drivers do not have ABI. Skip further
+				# processing if the map file is under
+				# drivers directory
+				continue
+			fi
 			if [ "$secname" = "unknown" ]
 			then
 				# Just inform the user of this occurrence, but
-- 
2.21.0


^ permalink raw reply	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2019-05-23 20:17 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-22 13:12 [dpdk-dev] [PATCH] devtools: skip the symbol check when map file under drivers Jerin Jacob Kollanukkaran
2019-05-22 13:40 ` Neil Horman
2019-05-22 14:12   ` Thomas Monjalon
2019-05-22 14:33     ` Neil Horman
  -- strict thread matches above, loose matches on Subject: below --
2019-05-23 14:21 Jerin Jacob Kollanukkaran
2019-05-23 17:57 ` Neil Horman
2019-05-23 18:59   ` Thomas Monjalon
2019-05-23 20:17     ` Neil Horman
2019-05-22 13:41 Jerin Jacob Kollanukkaran
2019-05-22 14:11 ` Neil Horman
2019-05-22 11:54 Jerin Jacob Kollanukkaran
2019-05-22 13:13 ` Neil Horman
2019-05-21 19:56 jerinj
2019-05-21 20:27 ` Neil Horman

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