Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] & [TECH TOPIC] Improve regression tracking

[Dan Williams <dan.j.williams@intel.com>]

On Wed, Jul 5, 2017 at 7:06 AM, Greg KH <greg@kroah.com> wrote:
> On Wed, Jul 05, 2017 at 09:27:57AM -0400, Steven Rostedt wrote:
>> Your "b" above is what I would like to push. But who's going to enforce
>> this? With 10,000 changes per release, and a lot of them are fixes, the
>> best we can do is the honor system. Start shaming people that don't
>> have a regression test along with a Fixes tag (but we don't want people
>> to fix bugs without adding that tag either). There is a fine line one
>> must walk between getting people to change their approaches to bugs and
>> regression tests, and pissing them off where they start doing the
>> opposite of what would be best for the community.
>
> I would bet, for the huge majority of our fixes, they are fixes for
> specific hardware, or workarounds for specific hardware issues.  Now
> writing tests for those is not an impossible task (look at what the i915
> developers have), but it is very very hard overall, especially if the
> base infrastructure isn't there to do it.
>
> For specific examples, here's the shortlog for fixes that went into
> drivers/usb/host/ for 4.12 after 4.12-rc1 came out.  Do you know of a
> way to write a test for these types of things?
>         usb: xhci: ASMedia ASM1042A chipset need shorts TX quirk
>         usb: xhci: Fix USB 3.1 supported protocol parsing
>         usb: host: xhci-plat: propagate return value of platform_get_irq()
>         xhci: Fix command ring stop regression in 4.11
>         xhci: remove GFP_DMA flag from allocation
>         USB: xhci: fix lock-inversion problem
>         usb: host: xhci-ring: don't need to clear interrupt pending for MSI enabled hcd
>         usb: host: xhci-mem: allocate zeroed Scratchpad Buffer
>         xhci: apply PME_STUCK_QUIRK and MISSING_CAS quirk for Denverton
>         usb: xhci: trace URB before giving it back instead of after
>         USB: host: xhci: use max-port define
>         USB: ehci-platform: fix companion-device leak
>         usb: r8a66597-hcd: select a different endpoint on timeout
>         usb: r8a66597-hcd: decrease timeout

I wrote some test infrastructure to go after xhci TRB boundary
conditions [1]. So, yes, some of these are possible to unit test, but
of course not all.

[1]: http://marc.info/?l=linux-usb&m=140872785411304&w=2