[PATCH 1/2] nvme-core: add ctrl state transition debug helper

[Chaitanya Kulkarni]

On 2/20/24 21:34, Chaitanya Kulkarni wrote:
> On 2/11/24 20:26, Chaitanya Kulkarni wrote:
>> NVMe controller state machine has total 7 states and 13 state transition
>> arcs. Debugging NVMeOF problems in the field is not straight-froward,
>> since it involves complex combination of connect/reconnect/kato/timeout
>> handlers etc scenarios.
>> We already have a helper in sysfs.c that reads the controller state, but
>> one has to constantly read the state in order understand the complete
>> state transition which is very inconvenient.
>>
>> It is often helpful to know full state transition of controller when
>> dealing with NVMeOF issues at the time of analyzing the trace.
>>
>> Add a helper that allows us to decode and print each controller state
>> transition :-
>>
>> blktests (master) # dmesg -c | grep nvme_change_ctrl_state
>> blktests (master) # nvme_trtype=tcp ./check nvme/048
>> nvme/048 (Test queue count changes on reconnect)             [passed]
>>       runtime  6.264s  ...  5.240s
>> blktests (master) # dmesg -c | grep nvme_change_ctrl_state
>> [17080.988689] nvme nvme0: nvme_change_ctrl_state new -> connecting
>> [17081.006623] nvme nvme0: nvme_change_ctrl_state connecting -> live
>> [17081.038313] nvme nvme0: nvme_change_ctrl_state live -> resetting
>> [17081.040730] nvme nvme0: nvme_change_ctrl_state resetting -> connecting
>> [17083.056750] nvme nvme0: nvme_change_ctrl_state connecting -> live
>> [17083.075906] nvme nvme0: nvme_change_ctrl_state live -> resetting
>> [17083.076112] nvme nvme0: nvme_change_ctrl_state resetting -> connecting
>> [17085.105270] nvme nvme0: nvme_change_ctrl_state connecting -> live
>> [17086.126484] nvme nvme0: nvme_change_ctrl_state live -> deleting
>> [17086.126506] nvme nvme0: nvme_change_ctrl_state deleting -> deleting (no IO)
>> blktests (master) #
>>
>> Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
>> ---
>>
> gentle ping ...
>
> -ck

gentle ping ...

-ck


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