Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Dmitry Osipenko]

09.01.2020 13:04, Thierry Reding ÐÐÑÐÑ:
> On Wed, Jan 08, 2020 at 06:07:46PM +0300, Dmitry Osipenko wrote:
>> 08.01.2020 15:51, Thierry Reding ÐÐÑÐÑ:
>>> On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
>>>> Hello,
>>>>
>>>> This is series fixes some problems that I spotted recently, secondly the
>>>> driver's code gets a cleanup. Please review and apply, thanks in advance!
>>>>
>>>> Changelog:
>>>>
>>>> v3: - In the review comment to v1 MichaÅ MirosÅaw suggested that "Prevent
>>>>       race conditions on channel's freeing" does changes that deserve to
>>>>       be separated into two patches. I factored out and improved tasklet
>>>>       releasing into this new patch:
>>>>
>>>>         dmaengine: tegra-apb: Clean up tasklet releasing
>>>>
>>>>     - The "Fix use-after-free" patch got an improved commit message.
>>>>
>>>> v2: - I took another look at the driver and spotted few more things that
>>>>       could be improved, which resulted in these new patches:
>>>>
>>>>         dmaengine: tegra-apb: Remove runtime PM usage
>>>>         dmaengine: tegra-apb: Clean up suspend-resume
>>>>         dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>         dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>> Dmitry Osipenko (13):
>>>>   dmaengine: tegra-apb: Fix use-after-free
>>>>   dmaengine: tegra-apb: Implement synchronization callback
>>>>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
>>>>   dmaengine: tegra-apb: Clean up tasklet releasing
>>>>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
>>>>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
>>>>   dmaengine: tegra-apb: Use devm_request_irq
>>>>   dmaengine: tegra-apb: Fix coding style problems
>>>>   dmaengine: tegra-apb: Remove runtime PM usage
>>>>   dmaengine: tegra-apb: Clean up suspend-resume
>>>>   dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>   dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>>  drivers/dma/Kconfig           |   2 +-
>>>>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
>>>>  2 files changed, 220 insertions(+), 263 deletions(-)
>>>
>>> Test results:
>>>   13 builds: 13 pass, 0 fail
>>>   12 boots:  11 pass, 1 fail
>>
>> I'm not sure how to interpret this result. Could you please explain what
>> that fail means?
> 
> Yeah, Jon and I have been discussing about whether to expose this as
> failure or not. Basically what I'm trying to do here is to provide
> automated test results. The way that I'm currently doing this is to run
> these patches through our internal test farm and if the tests succeed,
> send out the results and reply with a Tested-by: to all patches so that
> patchwork has a record of it.
> 
> So just the fact that the test results were sent means the tests passed.
> I do see now that that's not at all clear, so I'm going to have to tweak
> the summary a bit to clarify that.
> 
> I've also added something like this to the bottom of the summary:
> 
> 	Warnings:
> 	- 1 failure for board tegra186-p2771-0000 but tests passed
> 
> This is supposed to indicate that the one failure that you're seeing in
> the test results is an intermittent failure. Looking at the logs I see
> that at some point there was an intermittent boot failure for Jetson TX2
> but then the test farm rebooted the system and then it succeeded and ran
> the tests successfully.
> 
> So I guess in general this means that if you get that test summary and a
> list of Tested-by: replies to the patches, all is well. Unfortunately I
> don't really have a useful way of reporting failure, so I'm not sending
> out a summary in that case. That means you currently can't distinguish
> between whether the series hasn't been tested at all or whether it
> failed. Although, I have also started to use patchwork checks to track
> this in patchwork, so you could look at the patches in patchwork and see
> if they have been tested, and that does record success or failure.

The patchwork now says that all patches in this series failed.

Perhaps something needs to be done about filtering out the unimportant
intermittent noise.

>>>   38 tests:  38 pass, 0 fail
>>>
>>> Linux version: 5.5.0-rc5-gf9d40c056c0f
>>> Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
>>>                tegra186-p2771-0000, tegra194-p2972-0000,
>>>                tegra210-p2371-2180
>>>
>>
>> Will be awesome to see the detailed testing results, at least console
>> log like it was with NVTB.
> 
> Yeah, I'm working on that. It's the only reason I'm not sending out
> failure reports because it would just say that things failed without
> giving you any indication about why.
> 
> Currently the plan is to upload more detailed test results to a public
> location (perhaps github, like nvtb used to) and provide a link to them
> in patchwork and the test summary.
> 
> Do you think that would be helpful?

Yes, the full log is absolutely necessary in a case of problem.

> Anything else you think would be useful to have in these reports?

Optionally, there should be instructions about how to reproduce problem,
which includes rootfs, toolchain and etc.

> Or anything about the above that you think is impractical for you as a contributor?

The intermittent noise should be impractical to report in the short
logs, telling that tests failed. But probably it won't hurt to have a
warning, like you suggested above, and then also to have everything
reported in the detailed log.