Revert "Revert "net/rds: Revert "RDS: add reconnect retry scheme for stalled"

Revert "Revert "net/rds: Revert "RDS: add reconnect retry scheme for stalled"

This reverts commit fde8284e499b ("Revert "net/rds: Revert "RDS: add
reconnect retry scheme for stalled connections""").

Here is the commit message for the first revert:

<quote>
Commit 54312602fb26 ("RDS: add reconnect retry scheme for stalled
connections") introduces the rds_reconnect_timeout to retry the
connection establishment after sysctl_reconnect_retry_ms (default is
1000ms). Nevertheless, this proactive mechanism is overkilled and it
is causing long brownout time in the virtualized environment. In
short, below are the justifications why said commit is reverted.

a) The retry counter starts ticking after RDS received an ADDR_CHANGE
event. After receiving an ADDR_CHANGE event, RDS needs to perform shutdown
via shutdown_worker. Then, initiate a new connection via connect_worker.
Eventually, a CM REQ is only sent out after RDS received
RDMA_CM_EVENT_ADDR_RESOLVED and RDMA_CM_EVENT_ROUTE_RESOLVED events. If the
retry is made to cater for stalled connection due to missing CM messages,
the retry should only happen after a CM REQ is sent.  With the current
retry scheme (and with the default 1000 ms) that happens after ADDR_CHANGE
event, it introduces congestion in the single threaded workqueue.

b) Assuming that we modify the retry counter to start ticking after a
CM REQ message is sent out. By introducing another retry timeout, it
complicates the system tuning. Why? First, the
sysctl_reconnect_retry_ms relies on the underlying
cma_response_timeout. Any modication of cma_response_timeout requires
to tune sysctl_reconnect_retry_ms. Second, it is hard to find a
universal timing that fits all configurations (bare-metal,
virtualized, mixed environment, and homo/heterogenous system).
</quote>

Signed-off-by: Brian Maly <brian.maly@oracle.com>
Conflicts:
	net/rds/ib_cm.c
	net/rds/rdma_transport.c
	net/rds/threads.c

	Fixed checkpatch warnings.

Orabug: 28068627

Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>