netdev - Re: [PATCH v3 08/12] testing: net-drv: add basic shaper test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c5d0169a-ab1e-4431-a626-8b11cd7d9a9c@redhat.com>
Date: Mon, 12 Aug 2024 18:03:44 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Jakub Kicinski <kuba@...nel.org>, Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, Jiri Pirko <jiri@...nulli.us>,
 Madhu Chittim <madhu.chittim@...el.com>,
 Sridhar Samudrala <sridhar.samudrala@...el.com>,
 John Fastabend <john.fastabend@...il.com>,
 Sunil Kovvuri Goutham <sgoutham@...vell.com>,
 Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [PATCH v3 08/12] testing: net-drv: add basic shaper test

On 8/8/24 16:17, Jakub Kicinski wrote:
> On Thu, 8 Aug 2024 13:20:42 +0100 Simon Horman wrote:
>> Thanks again for the information.
>>
>> I have now taken another look at this problem.
>>
>> Firstly, my analysis is that the cause of the problem is a combination of
>> the way the patchset is constricted, and the way that the build tests (I
>> have focussed on build_allmodconfig_warn.sh [1]).
>>
>> [1] https://github.com/linux-netdev/nipa/blob/main/tests/patch/build_allmodconfig_warn/build_allmodconfig.sh
>>
>> What I believe happens is this: The patches 01/12 - 07/12 modify some
>> header files, adds a new Kconfig entry, and does a bunch of other normal
>> stuff. Each of those patches is tested in turn, and everything seems fine.
>>
>> Then we get to patch 08/12. The key thing about this patch is that it
>> enables the CONFIG_NET_SHAPER Kconfig option, in the context of an
>> allmodconfig build. That in turn modifies the headers
>> include/linux/netdevice.h and net/core/dev.h (and net/Makefile). Not in the
>> in terms of their on-disk contents changing, but rather in the case of the
>> header files, in terms of preprocessor output. And this is, I believe,
>> where everything goes wrong.
> 
> That's strange, make does not understand preprocessor, does it?

AFICS kbuild creates a file for each enabled knob under include/config/.
Then, for each kernel object target, it creates a .cmd file including 
the list of all dependencies. Such list comprises all the included files 
_and_ the relevant, mentioned "knob" file under include/config/

scripts/basic/fixdep is responsible for including the "knob files" in 
the dependency list.

To test the above:

   make drivers/net/ethernet/intel/ice/ice_main.o
   touch include/config/NET_SHAPER
   make V=2 drivers/net/ethernet/intel/ice/ice_main.o
   CALL    scripts/checksyscalls.sh - due to target is PHONY
   DESCEND objtool
   INSTALL libsubcmd_headers
   CC      drivers/net/ethernet/intel/ice/ice_main.o - due to: 
include/config/NET_SHAPER
Cheers,

Paolo