[bug report] NVMe/IB: reset_controller need more than 1min

[Sagi Grimberg]

>> Hi Yi Zhang,
>>
>> thanks for testing the patches.
>>
>> Can you provide more info on the time it took with both kernels ?
> 
> Hi Max
> Sorry for the late response, here are the test results/dmesg on
> debug/non-debug kernel with your patch:
> debug kernel: timeout
> # time nvme connect -t rdma -a 172.31.0.202 -s 4420 -n testnqn
> real    0m16.956s
> user    0m0.000s
> sys     0m0.237s
> # time nvme reset /dev/nvme0
> real    1m33.623s
> user    0m0.000s
> sys     0m0.024s
> # time nvme disconnect-all
> real    1m26.640s
> user    0m0.000s
> sys     0m9.969s
> 
> host dmesg:
> https://pastebin.com/8T3Lqtkn
> target dmesg:
> https://pastebin.com/KpFP7xG2
> 
> non-debug kernel: no timeout issue, but still 12s for reset, and 8s
> for disconnect
> host:
> # time nvme connect -t rdma -a 172.31.0.202 -s 4420 -n testnqn
> 
> real    0m4.579s
> user    0m0.000s
> sys     0m0.004s
> # time nvme reset /dev/nvme0
> 
> real    0m12.778s
> user    0m0.000s
> sys     0m0.006s
> # time nvme reset /dev/nvme0
> 
> real    0m12.793s
> user    0m0.000s
> sys     0m0.006s
> # time nvme reset /dev/nvme0
> 
> real    0m12.808s
> user    0m0.000s
> sys     0m0.006s
> # time nvme disconnect-all
> 
> real    0m8.348s
> user    0m0.000s
> sys     0m0.189s

These are very long times for a non-debug kernel...
Max, do you see the root cause for this?

Yi, does this happen with rxe/siw as well?