On Wed, Jan 29, 2020 at 01:28:19PM -0800, Brendan Higgins wrote: > On Wed, Jan 29, 2020 at 5:07 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: > > > > On Tue, 28 Jan 2020, Frank Rowand wrote: > > > > > On 1/28/20 1:19 AM, Brendan Higgins wrote: > > > > On Mon, Jan 27, 2020 at 9:40 AM Frank Rowand <frowand.list@xxxxxxxxx> wrote: > > > >> > > > >> On 1/23/20 4:40 PM, Brendan Higgins wrote: > > > >>> Sorry for the late reply. I am still catching up from being on vacation. > > > >>>>> On Mon, Jan 6, 2020 at 2:40 PM Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > > > >>>> It does beg the question if this means kunit is happy to not be a tool > > > >>>> to test pre basic setup stuff (terminology used in init.c, meaning prior > > > >>>> to running all init levels). I suspect this is the case. > > > >>> > > > >>> Not sure. I still haven't seen any cases where this is necessary, so I > > > >>> am not super worried about it. Regardless, I don't think this patchset > > > >>> really changes anything in that regard, we are moving from late_init > > > >>> to after late_init, so it isn't that big of a change for most use > > > >>> cases. > > > >>> > > > >>> Please share if you can think of some things that need to be tested in > > > >>> early init. > > > >> > > > >> I don't have a specific need for this right now. I had not thought about > > > >> how the current kunit implementation forces all kunit tests to run at a > > > >> specific initcall level before reading this email thread. > > > >> > > > >> I can see the value of being able to have some tests run at different > > > >> initcall levels to verify what functionality is available and working > > > >> at different points in the boot sequence. > > > > > > > > Let's cross that bridge when we get there. It should be fairly easy to > > > > add that functionality. > > > > > > Yes. I just wanted to add the thought to the back of your mind so that > > > it does not get precluded by future changes to the kunit architecture. > > > > > > > > > > >> But more important than early initcall levels, I do not want the > > > >> framework to prevent using or testing code and data that are marked > > > >> as '__init'. So it is important to retain a way to invoke the tests > > > >> while __init code and data are available, if there is also a change > > > >> to generally invoke the tests later. > > > > > > > > Definitely. For now that still works as long as you don't build KUnit > > > > as a module, but I think Alan's new patches which allow KUnit to be > > > > run at runtime via debugfs could cause some difficulty there. Again, > > > > > > Yes, Alan's patches are part of what triggered me thinking about the > > > issues I raised. > > > > > > > > > > As Brendan says, any such tests probably shouldn't be buildable > > as modules, but I wonder if we need to add some sort of way > > to ensure execution from debugfs is not allowed for such cases? The kernel's linker will ensure this doesn't happen by default, ie __init data called from non __init code gets a complaint at linker time today. *Iff* you are sure the code is proper, you *whitelist* it by adding the __ref tag to it. > > Even if a test suite is builtin, it can be executed via debugfs > > in the patches I sent out, allowing suites to be re-run. Sounds > > like we need a way to control that behaviour based on the > > desired test suite execution environment. > > I think that's true. > > > Say, for example, the "struct kunit_suite" definitions associated > > with the tests was marked as __initdata; are there any handy macros to > > identify it as being in the __init section? If so, we could simply > > avoid adding a "run" file to the debugfs representation for such > > suites. > > Failing that, perhaps we need some sort of flags field > > in "struct kunit_suite" to specify execution environment constraints? > > I think the former would be ideal, but the latter is acceptable as > well, assuming neither results in complaints from the compiler (I > guess we will find out for sure once we get a hold of the device tree > KUnit test). I'd split out tests in two different arrays, one with __init or __initdata one without. Likewise two dispatches, one for init and one for non-init data. > Luis, you mentioned your linker table work might be applicable for > dynamic post boot configuring of dispatching. Do you think this work > could help solve this problem? The Linux kernel table / section ranges code helps aggregate data into ELF sections in a generic way, that is, hacks we have been doing over years into a generic way. So it would be easier to read and implement. For instance see how in this commit the intent/goal of kprobe blacklists is a bit easier to read: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git/commit/?h=20170620-linker-tables-v8&id=b2662efa7c6a3c436961c07fa3082e8640f0e352 In particular DEFINE_LINKTABLE_INIT_DATA() use. I think Youd' want to use DEFINE_LINKTABLE_INIT_DATA() for code which you want to use to dispatch on init and and a DEFINE_LINKTABLE_DATA() for non-init code. If a dynamic dispatcher is used you'd opt out of the using for instance linktable_for_each() and instead use the data structure defined for however you want to disaptch your run time. Luis
