dm mpath: fix uninitialized 'pg_init_wait' waitqueue_head NULL pointer

Initialize all the scsi_dh related 'struct multipath' members regardless
of whether a scsi_dh is in use or not.

The subtle (and fragile) SCSI-assuming legacy code clearly needs further
decoupling from non-SCSI (and/or developer understanding).

Fixes: 8d47e65948dd ("dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks")
Reported-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 3fde9e9..87c404e 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -223,6 +223,16 @@ static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
 
        dm_table_set_type(ti->table, m->queue_mode);
 
+       /*
+        * Init fields that are only used when a scsi_dh is attached
+        * - must do this unconditionally (really doesn't hurt non-SCSI uses)
+        */
+       set_bit(MPATHF_QUEUE_IO, &m->flags);
+       atomic_set(&m->pg_init_in_progress, 0);
+       atomic_set(&m->pg_init_count, 0);
+       m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
+       init_waitqueue_head(&m->pg_init_wait);
+
        return 0;
 }
 
@@ -331,7 +341,6 @@ static void __switch_pg(struct multipath *m, struct priority_group *pg)
                set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
                set_bit(MPATHF_QUEUE_IO, &m->flags);
        } else {
-               /* FIXME: not needed if no scsi_dh is attached */
                clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
                clear_bit(MPATHF_QUEUE_IO, &m->flags);
        }
@@ -823,16 +832,6 @@ retain:
                         */
                        kfree(m->hw_handler_name);
                        m->hw_handler_name = attached_handler_name;
-
-                       /*
-                        * Init fields that are only used when a scsi_dh is attached
-                        */
-                       if (!test_and_set_bit(MPATHF_QUEUE_IO, &m->flags)) {
-                               atomic_set(&m->pg_init_in_progress, 0);
-                               atomic_set(&m->pg_init_count, 0);
-                               m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
-                               init_waitqueue_head(&m->pg_init_wait);
-                       }
                }
        }