Fix traverse nesting unlock bug.

[ccan] / ccan / tdb / traverse.c

diff --git a/ccan/tdb/traverse.c b/ccan/tdb/traverse.c
index 07b0c238587eb85fe3945b61b71dbd9dd0729d58..6397930b469da5385663cee6987b2568af5d0a03 100644 (file)
--- a/ccan/tdb/traverse.c
+++ b/ccan/tdb/traverse.c
@@ -169,6 +169,11 @@ static int tdb_traverse_internal(struct tdb_context *tdb,
                dbuf.dptr = key.dptr + rec.key_len;
                dbuf.dsize = rec.data_len;
 
+               tdb_trace(tdb, "traverse ");
+               tdb_trace_record(tdb, key);
+               tdb_trace_record(tdb, dbuf);
+               tdb_trace(tdb, "\n");
+
                /* Drop chain lock, call out */
                if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0) {
                        ret = -1;
@@ -177,6 +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"));;
@@ -187,6 +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)
@@ -207,15 +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->traverse_read--;
 
-       tdb_transaction_unlock(tdb);
+       if (tdb->traverse_read == 0) {
+               tdb_transaction_unlock(tdb);
+       }
 
        return ret;
 }
@@ -236,16 +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->traverse_write--;
 
-       tdb_transaction_unlock(tdb);
+       if (tdb->traverse_write == 0) {
+               tdb_transaction_unlock(tdb);
+       }
 
        return ret;
 }
@@ -264,12 +278,18 @@ TDB_DATA tdb_firstkey(struct tdb_context *tdb)
        tdb->travlocks.lock_rw = F_RDLCK;
 
        /* Grab first record: locks chain and returned record. */
-       if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0)
+       if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0) {
+               tdb_trace(tdb, "tdb_firstkey = ENOENT\n");
                return tdb_null;
+       }
        /* now read the key */
        key.dsize = rec.key_len;
        key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize);
 
+       tdb_trace(tdb, "tdb_firstkey = ");
+       tdb_trace_record(tdb, key);
+       tdb_trace(tdb, "\n");
+
        /* Unlock the hash chain of the record we just read. */
        if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_firstkey: error occurred while tdb_unlocking!\n"));
@@ -294,6 +314,9 @@ TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey)
                    || memcmp(k, oldkey.dptr, oldkey.dsize) != 0) {
                        /* No, it wasn't: unlock it and start from scratch */
                        if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) {
+                               tdb_trace(tdb, "tdb_nextkey ");
+                               tdb_trace_record(tdb, oldkey);
+                               tdb_trace(tdb, "= ENOENT\n");
                                SAFE_FREE(k);
                                return tdb_null;
                        }
@@ -310,8 +333,12 @@ TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey)
        if (!tdb->travlocks.off) {
                /* No previous element: do normal find, and lock record */
                tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), tdb->travlocks.lock_rw, &rec);
-               if (!tdb->travlocks.off)
+               if (!tdb->travlocks.off) {
+                       tdb_trace(tdb, "tdb_nextkey ");
+                       tdb_trace_record(tdb, oldkey);
+                       tdb_trace(tdb, "= ENOENT\n");
                        return tdb_null;
+               }
                tdb->travlocks.hash = BUCKET(rec.full_hash);
                if (tdb_lock_record(tdb, tdb->travlocks.off) != 0) {
                        TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: lock_record failed (%s)!\n", strerror(errno)));
@@ -333,6 +360,11 @@ TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey)
        /* Unlock the chain of old record */
        if (tdb_unlock(tdb, BUCKET(oldhash), tdb->travlocks.lock_rw) != 0)
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
+       tdb_trace(tdb, "tdb_nextkey ");
+       tdb_trace_record(tdb, oldkey);
+       tdb_trace(tdb, "= ");
+       tdb_trace_record(tdb, key);
+       tdb_trace(tdb, "\n");
        return key;
 }