ovsdb-idl: Consider all tables when computing expected cond seqno.

In ovsdb_idl_db_set_condition(), take into account all pending
condition changes for all tables when computing the db->cond_seqno at
which the monitor is expected to be updated.

In the following scenario, with two tables, A and B, the old code
performed the following steps:
1. Initial db->cond_seqno = X.
2. Client changes condition for table A:
   - A->new_cond gets set
   - expected cond seqno returned to the client: X + 1
3. ovsdb-idl sends the monitor_cond_change for table A
   - A->req_cond <- A->new_cond
4. Client changes condition for table B:
   - B->new_cond gets set
   - expected cond seqno returned to the client: X + 1
   - however, because the condition change at step 3 is still not replied
     to, table B's monitor_cond_change request is not sent yet.
5. ovsdb-idl receives the reply for the condition change at step 3:
   - db->cond_seqno <- X + 1
6. ovsdb-idl sends the monitor_cond_change for table B
7. ovsdb-idl receives the reply for the condition change at step 6:
  - db->cond_seqno <- X + 2

The client was incorrectly informed that it will have all relevant
updates for table B at seqno X + 1 while actually that happens later, at
seqno X + 2.

Fixes: 46437c5232bd ("ovsdb-idl: Enhance conditional monitoring API")
Acked-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>
(cherry picked from commit b5bb044fbe4c1395dcde5cc7d5081ef0099bb8b3)
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

1 files changed, 21 insertions, 3 deletions

diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
index 2fc8a91e3..325050f21 100644
--- a/lib/ovsdb-idl.c
+++ b/lib/ovsdb-idl.c
@@ -1575,7 +1575,6 @@ ovsdb_idl_db_set_condition(struct ovsdb_idl_db *db,
 {
     struct ovsdb_idl_condition *table_cond;
     struct ovsdb_idl_table *table = ovsdb_idl_db_table_from_class(db, tc);
-    unsigned int curr_seqno = db->cond_seqno;
 
     /* Compare the new condition to the last known condition which can be
      * either "new" (not sent yet), "requested" or "acked", in this order.
@@ -1596,8 +1595,27 @@ ovsdb_idl_db_set_condition(struct ovsdb_idl_db *db,
     }
 
     /* Conditions will be up to date when we receive replies for already
-     * requested and new conditions, if any. */
-    return curr_seqno + (table->new_cond ? 1 : 0) + (table->req_cond ? 1 : 0);
+     * requested and new conditions, if any.  This includes condition change
+     * requests for other tables too.
+     */
+    if (table->new_cond) {
+        /* New condition will be sent out after all already requested ones
+         * are acked.
+         */
+        bool any_req_cond = false;
+        for (size_t i = 0; i < db->class_->n_tables; i++) {
+            if (db->tables[i].req_cond) {
+                any_req_cond = true;
+                break;
+            }
+        }
+        return db->cond_seqno + any_req_cond + 1;
+    } else {
+        /* Already requested conditions should be up to date at
+         * db->cond_seqno + 1 while acked conditions are already up to date.
+         */
+        return db->cond_seqno + !!table->req_cond;
+    }
 }
 
 /* Sets the replication condition for 'tc' in 'idl' to 'condition' and