Fix traverse nesting unlock bug.

[ccan] / ccan / tdb / traverse.c

diff --git a/ccan/tdb/traverse.c b/ccan/tdb/traverse.c
index 6bbaac8d635b96dc351b52a386ab02ea3d8eb2e8..6397930b469da5385663cee6987b2568af5d0a03 100644 (file)
--- a/ccan/tdb/traverse.c
+++ b/ccan/tdb/traverse.c
@@ -182,6 +182,7 @@ static int tdb_traverse_internal(struct tdb_context *tdb,
                }
                if (fn && fn(tdb, key, dbuf, private_data)) {
                        /* They want us to terminate traversal */
+                       tdb_trace(tdb, "tdb_traverse_end = %i\n", count);
                        ret = count;
                        if (tdb_unlock_record(tdb, tl->off) != 0) {
                                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));;
@@ -192,6 +193,7 @@ static int tdb_traverse_internal(struct tdb_context *tdb,
                }
                SAFE_FREE(key.dptr);
        }
+       tdb_trace(tdb, "tdb_traverse_end\n");
 out:
        tdb->travlocks.next = tl->next;
        if (ret < 0)
@@ -212,17 +214,18 @@ int tdb_traverse_read(struct tdb_context *tdb,
 
        /* we need to get a read lock on the transaction lock here to
           cope with the lock ordering semantics of solaris10 */
-       if (tdb_transaction_lock(tdb, F_RDLCK)) {
+       if (tdb->traverse_read == 0 && tdb_transaction_lock(tdb, F_RDLCK)) {
                return -1;
        }
 
        tdb->traverse_read++;
        tdb_trace(tdb, "tdb_traverse_read_start\n");
        ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
-       tdb_trace(tdb, "tdb_traverse_end = %i\n", ret);
        tdb->traverse_read--;
 
-       tdb_transaction_unlock(tdb);
+       if (tdb->traverse_read == 0) {
+               tdb_transaction_unlock(tdb);
+       }
 
        return ret;
 }
@@ -243,18 +246,20 @@ int tdb_traverse(struct tdb_context *tdb,
        if (tdb->read_only || tdb->traverse_read) {
                return tdb_traverse_read(tdb, fn, private_data);
        }
-       
-       if (tdb_transaction_lock(tdb, F_WRLCK)) {
+
+       /* Nested traversals: transaction lock doesn't nest. */
+       if (tdb->traverse_write == 0 && tdb_transaction_lock(tdb, F_WRLCK)) {
                return -1;
        }
 
        tdb->traverse_write++;
        tdb_trace(tdb, "tdb_traverse_start\n");
        ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
-       tdb_trace(tdb, "tdb_traverse_end = %i\n", ret);
        tdb->traverse_write--;
 
-       tdb_transaction_unlock(tdb);
+       if (tdb->traverse_write == 0) {
+               tdb_transaction_unlock(tdb);
+       }
 
        return ret;
 }