[PATCH v2] tests/nvme: Add admin-passthru+reset race test

[Keith Busch]

[cc'ing Klaus]

On Mon, Nov 21, 2022 at 03:49:45PM -0700, Jonathan Derrick wrote:
> On 11/21/2022 3:34 PM, Jonathan Derrick wrote:
> > On 11/21/2022 1:55 PM, Keith Busch wrote:
> >> On Thu, Nov 17, 2022 at 02:22:10PM -0700, Jonathan Derrick wrote:
> >>> I seem to have isolated the error mechanism for older kernels, but 6.2.0-rc2
> >>> reliably segfaults my QEMU instance (something else to look into) and I don't
> >>> have any 'real' hardware to test this on at the moment. It looks like several
> >>> passthru commands are able to enqueue prior/during/after resetting/connecting.
> >>
> >> I'm not seeing any problem with the latest nvme-qemu after several dozen
> >> iterations of this test case. In that environment, the formats and
> >> resets complete practically synchronously with the call, so everything
> >> proceeds quickly. Is there anything special I need to change?
> >>  
> > I can still repro this with nvme-fixes tag, so I'll have to dig into it myself
> Here's a backtrace:
> 
> Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7ffff7554400 (LWP 531154)]
> 0x000055555597a9d5 in nvme_ctrl (req=0x7fffec892780) at ../hw/nvme/nvme.h:539
> 540         return sq->ctrl;
> (gdb) backtrace
> #0  0x000055555597a9d5 in nvme_ctrl (req=0x7fffec892780) at ../hw/nvme/nvme.h:539
> #1  0x0000555555994360 in nvme_format_bh (opaque=0x5555579dd000) at ../hw/nvme/ctrl.c:5852

Thanks, looks like a race between the admin queue format's bottom half,
and the controller reset tearing down that queue. I'll work with Klaus
on that qemu side (looks like a well placed qemu_bh_cancel() should do
it).