[SPDK] Re: Print backtrace in SPDK

Hi Wenhua,

Which applications are you using from SPDK?  
1 SPDK NVMe-oF target in target side?
2  SPDK NVMe perf or others?

For nvmf_tcp_close_qpair will be called in the following possible cases (not all listed) for TCP transport. But it will be called by spdk_nvmf_qpair_disconnect as the entry.

1  qpair is not in polling group
spdk_nvmf_qpair_disconnect
	nvmf_transport_qpair_fini

2  spdk_nvmf_qpair_disconnect
		....
	_nvmf_qpair_destroy
		nvmf_transport_qpair_fini
			..
			nvmf_tcp_close_qpair


3  spdk_nvmf_qpair_disconnect
		....
	_nvmf_qpair_destroy
		_nvmf_ctrlr_free_from_qpair	
			_nvmf_transport_qpair_fini
				..
				nvmf_tcp_close_qpair


spdk_nvmf_qpair_disconnect is called by nvmf_tcp_qpair_disconnect in tcp.c. nvmf_tcp_qpair_disconnect is called in the following cases:

(1) _pdu_write_done (if there is error for write);
(2) nvmf_tcp_qpair_handle_timeout.( No response from initiator in 30s if targets sends c2h_term_req)
(3) nvmf_tcp_capsule_cmd_hdr_handle. (Cannot get tcp req)
(4) nvmf_tcp_sock_cb.   TCP PDU related handling issue. 


Also in lib/nvmf/ctrlr.c Target side has a timer poller: nvmf_ctrlr_keep_alive_poll. If there is no keep alive command sent from host, it will call spdk_nvmf_qpair_disconnect in related polling group assoicated with the controller.


Best Regards
Ziye Yang 

-----Original Message-----
From: Wenhua Liu <liuw(a)vmware.com> 
Sent: Saturday, August 22, 2020 3:15 PM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: [SPDK] Print backtrace in SPDK

Hi,

Does anyone know if there is a function in SPDK that prints the backtrace?

I run into a “Connection Reset by Peer” issue on host side when testing NVMe/TCP. I identified it’s because some queue pairs are closed unexpectedly by calling nvmf_tcp_close_qpair, but I could not figure out how/why this function is called. I thought if the backtrace can be printed when calling this function, it might be helpful to me to find the root cause.

Thanks,
-Wenhua
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