net/rds: Keep track of and wait for FRWR segments in use upon shutdown

Since "rds_ib_free_frmr" and "rds_ib_free_frmr_list" simply put
the FRMR memory segments on the "drop_list" or "free_list",
and it is the job of "rds_ib_flush_mr_pool" to reap those entries
by ultimately issuing a "IB_WR_LOCAL_INV" work-request,
we need to trigger and then wait for all those memory segments
attached to a particular connection to be fully released before
we can move on to release the QP, CQ, etc.

So we make "rds_ib_conn_path_shutdown" wait for one more
atomic_t called "i_fastreg_inuse_count" that keeps track of how
many FRWR memory segments are out there marked "FRMR_IS_INUSE"
(and also wake_up rds_ib_ring_empty_wait, as they go away).

Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 8891822eba4f..1b6fd6c8b12b 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -40,6 +40,7 @@
 #include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
+#include "ib_mr.h"
 
 /*
  * Set the selected protocol version
@@ -993,6 +994,11 @@ void rds_ib_conn_path_shutdown(struct rds_conn_path *cp)
                                 ic->i_cm_id, err);
                 }
 
+                /* kick off "flush_worker" for all pools in order to reap
+                 * all FRMR registrations that are still marked "FRMR_IS_INUSE"
+                 */
+                rds_ib_flush_mrs();
+
                 /*
                  * We want to wait for tx and rx completion to finish
                  * before we tear down the connection, but we have to be
@@ -1005,6 +1011,7 @@ void rds_ib_conn_path_shutdown(struct rds_conn_path *cp)
                 wait_event(rds_ib_ring_empty_wait,
                            rds_ib_ring_empty(&ic->i_recv_ring) &&
                            (atomic_read(&ic->i_signaled_sends) == 0) &&
+                           (atomic_read(&ic->i_fastreg_inuse_count) == 0) &&
                            (atomic_read(&ic->i_fastreg_wrs) == RDS_IB_DEFAULT_FR_WR));
                 tasklet_kill(&ic->i_send_tasklet);
                 tasklet_kill(&ic->i_recv_tasklet);