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

On Wed, Jul 5, 2017 at 7:06 AM, Greg KH [off-list ref] wrote:

On Wed, Jul 05, 2017 at 09:27:57AM -0400, Steven Rostedt wrote:

quoted

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