When a command arrives and no requests are available, the socket
recv state machine sits in the RECV_STATE_AWAIT_REQ state until another
network event occurs. If this I/O was the last one sent, this leaves the
target hung. To fix this, when a request is completed, kick the state
machine to make forward progress.
In practice, this can only occur once the pdu send acknowledgements are
asynchronous relative to arriving commands. That only begins happening
with the use of MSG_ZEROCOPY. When MSG_ZEROCOPY is turned on, it's
possible receive the next PDU in a chain for a command prior to seeing
the acknowledgement that the response that triggered that PDU actually
sent.
Change-Id: I556f31ad56970d36aa3538cfde375d35f3d4e551
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/480002
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
f84c916c41