libceph: flush msgr queue during mon_client shutdown

We need to flush the msgr workqueue during mon_client shutdown to
ensure that any work affecting our embedded ceph_connection is
finished so that we can be safely destroyed.

Previously, we were flushing the work queue after osd_client
shutdown and before mon_client shutdown to ensure that any osd
connection refs to authorizers are flushed.  Remove the redundant
flush, and document in the comment that the mon_client flush is
needed to cover that case as well.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
(cherry picked from commit f3dea7edd3d449fe7a6d402c1ce56a294b985261)

2 files changed, 8 insertions, 7 deletions

diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index a776f751edbf..ba4323bce0e9 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -504,13 +504,6 @@ void ceph_destroy_client(struct ceph_client *client)
         /* unmount */
         ceph_osdc_stop(&client->osdc);
 
-        /*
-         * make sure osd connections close out before destroying the
-         * auth module, which is needed to free those connections'
-         * ceph_authorizers.
-         */
-        ceph_msgr_flush();
-
         ceph_monc_stop(&client->monc);
 
         ceph_debugfs_client_cleanup(client);
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 10d6008d31f2..d0649a9655be 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -847,6 +847,14 @@ void ceph_monc_stop(struct ceph_mon_client *monc)
 
         mutex_unlock(&monc->mutex);
 
+        /*
+         * flush msgr queue before we destroy ourselves to ensure that:
+         *  - any work that references our embedded con is finished.
+         *  - any osd_client or other work that may reference an authorizer
+         *    finishes before we shut down the auth subsystem.
+         */
+        ceph_msgr_flush();
+
         ceph_auth_destroy(monc->auth);
 
         ceph_msg_put(monc->m_auth);