If setup_multipath() is called before the waiter thread has started,
there is a window where a dm event can occur between when
setup_multipath() updates the device state and when the waiter thread
starts waiting for new events, causing the new event to be missed and
the multipath device to not get updated.

Signed-off-by: Benjamin Marzinski <bmarz...@redhat.com>
---
 multipathd/main.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/multipathd/main.c b/multipathd/main.c
index 94b2406..efc39d7 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -321,7 +321,7 @@ set_multipath_wwid (struct multipath * mpp)
 }
 
 static int
-update_map (struct multipath *mpp, struct vectors *vecs)
+update_map (struct multipath *mpp, struct vectors *vecs, int new_map)
 {
        int retries = 3;
        char params[PARAMS_SIZE] = {0};
@@ -351,6 +351,12 @@ retry:
        dm_lib_release();
 
 fail:
+       if (new_map && (retries < 0 || start_waiter_thread(mpp, vecs))) {
+               condlog(0, "%s: failed to create new map", mpp->alias);
+               remove_map(mpp, vecs, 1);
+               return 1;
+       }
+
        if (setup_multipath(vecs, mpp))
                return 1;
 
@@ -395,12 +401,9 @@ add_map_without_path (struct vectors *vecs, char *alias)
 
        vector_set_slot(vecs->mpvec, mpp);
 
-       if (update_map(mpp, vecs) != 0) /* map removed */
+       if (update_map(mpp, vecs, 1) != 0) /* map removed */
                return NULL;
 
-       if (start_waiter_thread(mpp, vecs))
-               goto out;
-
        return mpp;
 out:
        remove_map(mpp, vecs, PURGE_VEC);
@@ -554,7 +557,7 @@ ev_add_map (char * dev, char * alias, struct vectors * vecs)
                if (mpp->wait_for_udev > 1) {
                        condlog(2, "%s: performing delayed actions",
                                mpp->alias);
-                       if (update_map(mpp, vecs))
+                       if (update_map(mpp, vecs, 0))
                                /* setup multipathd removed the map */
                                return 1;
                }
@@ -865,6 +868,11 @@ retry:
        }
        dm_lib_release();
 
+       if ((mpp->action == ACT_CREATE ||
+            (mpp->action == ACT_NOTHING && start_waiter && !mpp->waiter)) &&
+           start_waiter_thread(mpp, vecs))
+                       goto fail_map;
+
        /*
         * update our state from kernel regardless of create or reload
         */
@@ -873,11 +881,6 @@ retry:
 
        sync_map_state(mpp);
 
-       if ((mpp->action == ACT_CREATE ||
-            (mpp->action == ACT_NOTHING && start_waiter && !mpp->waiter)) &&
-           start_waiter_thread(mpp, vecs))
-                       goto fail_map;
-
        if (retries >= 0) {
                condlog(2, "%s [%s]: path added to devmap %s",
                        pp->dev, pp->dev_t, mpp->alias);
@@ -1479,7 +1482,8 @@ missing_uev_wait_tick(struct vectors *vecs)
                if (mpp->wait_for_udev && --mpp->uev_wait_tick <= 0) {
                        timed_out = 1;
                        condlog(0, "%s: timeout waiting on creation uevent. 
enabling reloads", mpp->alias);
-                       if (mpp->wait_for_udev > 1 && update_map(mpp, vecs)) {
+                       if (mpp->wait_for_udev > 1 &&
+                           update_map(mpp, vecs, 0)) {
                                /* update_map removed map */
                                i--;
                                continue;
@@ -1511,7 +1515,7 @@ ghost_delay_tick(struct vectors *vecs)
                        condlog(0, "%s: timed out waiting for active path",
                                mpp->alias);
                        mpp->force_udev_reload = 1;
-                       if (update_map(mpp, vecs) != 0) {
+                       if (update_map(mpp, vecs, 0) != 0) {
                                /* update_map removed map */
                                i--;
                                continue;
@@ -2169,14 +2173,13 @@ configure (struct vectors * vecs)
         * start dm event waiter threads for these new maps
         */
        vector_foreach_slot(vecs->mpvec, mpp, i) {
-               if (setup_multipath(vecs, mpp)) {
-                       i--;
-                       continue;
-               }
                if (start_waiter_thread(mpp, vecs)) {
                        remove_map(mpp, vecs, 1);
                        i--;
+                       continue;
                }
+               if (setup_multipath(vecs, mpp))
+                       i--;
        }
        return 0;
 }
-- 
2.7.4

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