Commited backport from master to 1.2.24 (bug https://bugs.freedesktop.org/show_bug.cgi?id=17754) - patch to fix thread safety in protected_change_timeout for further review.

(Portage version: 2.2_rc67/cvs/Linux x86_64)

1 files changed, 393 insertions, 0 deletions

diff --git a/sys-apps/dbus/files/dbus-1.2.24-thread-safety.patch b/sys-apps/dbus/files/dbus-1.2.24-thread-safety.patch
new file mode 100644
index 000000000000..79ffd51e2dd0
--- /dev/null
+++ b/sys-apps/dbus/files/dbus-1.2.24-thread-safety.patch
@@ -0,0 +1,393 @@
+https://bugs.freedesktop.org/show_bug.cgi?id=17754
+
+backport from 6ff1d079316cb730a54b4e0e95bd3e6e31f439de (master)
+
+diff -ru ../dbus-1.2.24/dbus/dbus-connection.c ./dbus/dbus-connection.c
+--- ../dbus-1.2.24/dbus/dbus-connection.c	2010-03-23 20:01:32.000000000 +0100
++++ ./dbus/dbus-connection.c	2010-08-04 07:20:00.310381625 +0200
+@@ -73,6 +73,14 @@
+     _dbus_mutex_unlock ((connection)->mutex);                                            \
+   } while (0)
+ 
++#define SLOTS_LOCK(connection) do {                     \
++    _dbus_mutex_lock ((connection)->slot_mutex);        \
++  } while (0)
++
++#define SLOTS_UNLOCK(connection) do {                   \
++    _dbus_mutex_unlock ((connection)->slot_mutex);      \
++  } while (0)
++
+ #define DISPATCH_STATUS_NAME(s)                                            \
+                      ((s) == DBUS_DISPATCH_COMPLETE ? "complete" :         \
+                       (s) == DBUS_DISPATCH_DATA_REMAINS ? "data remains" : \
+@@ -257,6 +265,7 @@
+   
+   DBusList *filter_list;        /**< List of filters. */
+ 
++  DBusMutex *slot_mutex;        /**< Lock on slot_list so overall connection lock need not be taken */
+   DBusDataSlotList slot_list;   /**< Data stored by allocated integer ID */
+ 
+   DBusHashTable *pending_replies;  /**< Hash of message serials to #DBusPendingCall. */  
+@@ -647,39 +656,42 @@
+                         DBusWatchToggleFunction toggle_function,
+                         dbus_bool_t             enabled)
+ {
+-  DBusWatchList *watches;
+   dbus_bool_t retval;
+-  
++
+   HAVE_LOCK_CHECK (connection);
+ 
+-  /* This isn't really safe or reasonable; a better pattern is the "do everything, then
+-   * drop lock and call out" one; but it has to be propagated up through all callers
++  /* The original purpose of protected_change_watch() was to hold a
++   * ref on the connection while dropping the connection lock, then
++   * calling out to the app.  This was a broken hack that did not
++   * work, since the connection was in a hosed state (no WatchList
++   * field) while calling out.
++   *
++   * So for now we'll just keep the lock while calling out. This means
++   * apps are not allowed to call DBusConnection methods inside a
++   * watch function or they will deadlock.
++   *
++   * The "real fix" is to use the _and_unlock() pattern found
++   * elsewhere in the code, to defer calling out to the app until
++   * we're about to drop locks and return flow of control to the app
++   * anyway.
++   *
++   * See http://lists.freedesktop.org/archives/dbus/2007-July/thread.html#8144
+    */
+-  
+-  watches = connection->watches;
+-  if (watches)
+-    {
+-      connection->watches = NULL;
+-      _dbus_connection_ref_unlocked (connection);
+-      CONNECTION_UNLOCK (connection);
+ 
++  if (connection->watches)
++    {
+       if (add_function)
+-        retval = (* add_function) (watches, watch);
++        retval = (* add_function) (connection->watches, watch);
+       else if (remove_function)
+         {
+           retval = TRUE;
+-          (* remove_function) (watches, watch);
++          (* remove_function) (connection->watches, watch);
+         }
+       else
+         {
+           retval = TRUE;
+-          (* toggle_function) (watches, watch, enabled);
++          (* toggle_function) (connection->watches, watch, enabled);
+         }
+-      
+-      CONNECTION_LOCK (connection);
+-      connection->watches = watches;
+-      _dbus_connection_unref_unlocked (connection);
+-
+       return retval;
+     }
+   else
+@@ -768,39 +780,42 @@
+                           DBusTimeoutToggleFunction toggle_function,
+                           dbus_bool_t               enabled)
+ {
+-  DBusTimeoutList *timeouts;
+   dbus_bool_t retval;
+-  
++
+   HAVE_LOCK_CHECK (connection);
+ 
+-  /* This isn't really safe or reasonable; a better pattern is the "do everything, then
+-   * drop lock and call out" one; but it has to be propagated up through all callers
++  /* The original purpose of protected_change_timeout() was to hold a
++   * ref on the connection while dropping the connection lock, then
++   * calling out to the app.  This was a broken hack that did not
++   * work, since the connection was in a hosed state (no TimeoutList
++   * field) while calling out.
++   *
++   * So for now we'll just keep the lock while calling out. This means
++   * apps are not allowed to call DBusConnection methods inside a
++   * timeout function or they will deadlock.
++   *
++   * The "real fix" is to use the _and_unlock() pattern found
++   * elsewhere in the code, to defer calling out to the app until
++   * we're about to drop locks and return flow of control to the app
++   * anyway.
++   *
++   * See http://lists.freedesktop.org/archives/dbus/2007-July/thread.html#8144
+    */
+-  
+-  timeouts = connection->timeouts;
+-  if (timeouts)
+-    {
+-      connection->timeouts = NULL;
+-      _dbus_connection_ref_unlocked (connection);
+-      CONNECTION_UNLOCK (connection);
+ 
++  if (connection->timeouts)
++    {
+       if (add_function)
+-        retval = (* add_function) (timeouts, timeout);
++        retval = (* add_function) (connection->timeouts, timeout);
+       else if (remove_function)
+         {
+           retval = TRUE;
+-          (* remove_function) (timeouts, timeout);
++          (* remove_function) (connection->timeouts, timeout);
+         }
+       else
+         {
+           retval = TRUE;
+-          (* toggle_function) (timeouts, timeout, enabled);
++          (* toggle_function) (connection->timeouts, timeout, enabled);
+         }
+-      
+-      CONNECTION_LOCK (connection);
+-      connection->timeouts = timeouts;
+-      _dbus_connection_unref_unlocked (connection);
+-
+       return retval;
+     }
+   else
+@@ -1239,6 +1254,10 @@
+   if (connection->io_path_cond == NULL)
+     goto error;
+ 
++  _dbus_mutex_new_at_location (&connection->slot_mutex);
++  if (connection->slot_mutex == NULL)
++    goto error;
++
+   disconnect_message = dbus_message_new_signal (DBUS_PATH_LOCAL,
+                                                 DBUS_INTERFACE_LOCAL,
+                                                 "Disconnected");
+@@ -1315,6 +1334,7 @@
+       _dbus_mutex_free_at_location (&connection->mutex);
+       _dbus_mutex_free_at_location (&connection->io_path_mutex);
+       _dbus_mutex_free_at_location (&connection->dispatch_mutex);
++      _dbus_mutex_free_at_location (&connection->slot_mutex);
+       dbus_free (connection);
+     }
+   if (pending_replies)
+@@ -2558,9 +2578,14 @@
+   
+   /* The connection lock is better than the global
+    * lock in the atomic increment fallback
++   *
++   * (FIXME but for now we always use the atomic version,
++   * to avoid taking the connection lock, due to
++   * the mess with set_timeout_functions()/set_watch_functions()
++   * calling out to the app without dropping locks)
+    */
+   
+-#ifdef DBUS_HAVE_ATOMIC_INT
++#if 1
+   _dbus_atomic_inc (&connection->refcount);
+ #else
+   CONNECTION_LOCK (connection);
+@@ -2672,6 +2697,8 @@
+   _dbus_mutex_free_at_location (&connection->io_path_mutex);
+   _dbus_mutex_free_at_location (&connection->dispatch_mutex);
+ 
++  _dbus_mutex_free_at_location (&connection->slot_mutex);
++
+   _dbus_mutex_free_at_location (&connection->mutex);
+   
+   dbus_free (connection);
+@@ -2706,9 +2733,14 @@
+   
+   /* The connection lock is better than the global
+    * lock in the atomic increment fallback
++   *
++   * (FIXME but for now we always use the atomic version,
++   * to avoid taking the connection lock, due to
++   * the mess with set_timeout_functions()/set_watch_functions()
++   * calling out to the app without dropping locks)
+    */
+   
+-#ifdef DBUS_HAVE_ATOMIC_INT
++#if 1
+   last_unref = (_dbus_atomic_dec (&connection->refcount) == 1);
+ #else
+   CONNECTION_LOCK (connection);
+@@ -4652,9 +4684,11 @@
+  * should be that dbus_connection_set_watch_functions() has no effect,
+  * but the add_function and remove_function may have been called.
+  *
+- * @todo We need to drop the lock when we call the
+- * add/remove/toggled functions which can be a side effect
+- * of setting the watch functions.
++ * @note The thread lock on DBusConnection is held while
++ * watch functions are invoked, so inside these functions you
++ * may not invoke any methods on DBusConnection or it will deadlock.
++ * See the comments in the code or http://lists.freedesktop.org/archives/dbus/2007-July/tread.html#8144
++ * if you encounter this issue and want to attempt writing a patch.
+  * 
+  * @param connection the connection.
+  * @param add_function function to begin monitoring a new descriptor.
+@@ -4673,42 +4707,17 @@
+                                      DBusFreeFunction             free_data_function)
+ {
+   dbus_bool_t retval;
+-  DBusWatchList *watches;
+ 
+   _dbus_return_val_if_fail (connection != NULL, FALSE);
+   
+   CONNECTION_LOCK (connection);
+ 
+-#ifndef DBUS_DISABLE_CHECKS
+-  if (connection->watches == NULL)
+-    {
+-      _dbus_warn_check_failed ("Re-entrant call to %s is not allowed\n",
+-                               _DBUS_FUNCTION_NAME);
+-      return FALSE;
+-    }
+-#endif
+-  
+-  /* ref connection for slightly better reentrancy */
+-  _dbus_connection_ref_unlocked (connection);
+-
+-  /* This can call back into user code, and we need to drop the
+-   * connection lock when it does. This is kind of a lame
+-   * way to do it.
+-   */
+-  watches = connection->watches;
+-  connection->watches = NULL;
+-  CONNECTION_UNLOCK (connection);
+-
+-  retval = _dbus_watch_list_set_functions (watches,
++  retval = _dbus_watch_list_set_functions (connection->watches,
+                                            add_function, remove_function,
+                                            toggled_function,
+                                            data, free_data_function);
+-  CONNECTION_LOCK (connection);
+-  connection->watches = watches;
+-  
++
+   CONNECTION_UNLOCK (connection);
+-  /* drop our paranoid refcount */
+-  dbus_connection_unref (connection);
+   
+   return retval;
+ }
+@@ -4738,6 +4747,12 @@
+  * given remove_function.  The timer interval may change whenever the
+  * timeout is added, removed, or toggled.
+  *
++ * @note The thread lock on DBusConnection is held while
++ * timeout functions are invoked, so inside these functions you
++ * may not invoke any methods on DBusConnection or it will deadlock.
++ * See the comments in the code or http://lists.freedesktop.org/archives/dbus/2007-July/thread.html#8144
++ * if you encounter this issue and want to attempt writing a patch.
++ *
+  * @param connection the connection.
+  * @param add_function function to add a timeout.
+  * @param remove_function function to remove a timeout.
+@@ -4755,38 +4770,17 @@
+ 					 DBusFreeFunction           free_data_function)
+ {
+   dbus_bool_t retval;
+-  DBusTimeoutList *timeouts;
+ 
+   _dbus_return_val_if_fail (connection != NULL, FALSE);
+   
+   CONNECTION_LOCK (connection);
+ 
+-#ifndef DBUS_DISABLE_CHECKS
+-  if (connection->timeouts == NULL)
+-    {
+-      _dbus_warn_check_failed ("Re-entrant call to %s is not allowed\n",
+-                               _DBUS_FUNCTION_NAME);
+-      return FALSE;
+-    }
+-#endif
+-  
+-  /* ref connection for slightly better reentrancy */
+-  _dbus_connection_ref_unlocked (connection);
+-
+-  timeouts = connection->timeouts;
+-  connection->timeouts = NULL;
+-  CONNECTION_UNLOCK (connection);
+-  
+-  retval = _dbus_timeout_list_set_functions (timeouts,
++  retval = _dbus_timeout_list_set_functions (connection->timeouts,
+                                              add_function, remove_function,
+                                              toggled_function,
+                                              data, free_data_function);
+-  CONNECTION_LOCK (connection);
+-  connection->timeouts = timeouts;
+-  
++
+   CONNECTION_UNLOCK (connection);
+-  /* drop our paranoid refcount */
+-  dbus_connection_unref (connection);
+ 
+   return retval;
+ }
+@@ -5749,6 +5743,15 @@
+  * the connection is finalized. The slot number
+  * must have been allocated with dbus_connection_allocate_data_slot().
+  *
++ * @note This function does not take the
++ * main thread lock on DBusConnection, which allows it to be
++ * used from inside watch and timeout functions. (See the
++ * note in docs for dbus_connection_set_watch_functions().)
++ * A side effect of this is that you need to know there's
++ * a reference held on the connection while invoking
++ * dbus_connection_set_data(), or the connection could be
++ * finalized during dbus_connection_set_data().
++ *
+  * @param connection the connection
+  * @param slot the slot number
+  * @param data the data to store
+@@ -5768,14 +5771,14 @@
+   _dbus_return_val_if_fail (connection != NULL, FALSE);
+   _dbus_return_val_if_fail (slot >= 0, FALSE);
+   
+-  CONNECTION_LOCK (connection);
++  SLOTS_LOCK (connection);
+ 
+   retval = _dbus_data_slot_list_set (&slot_allocator,
+                                      &connection->slot_list,
+                                      slot, data, free_data_func,
+                                      &old_free_func, &old_data);
+   
+-  CONNECTION_UNLOCK (connection);
++  SLOTS_UNLOCK (connection);
+ 
+   if (retval)
+     {
+@@ -5791,6 +5794,15 @@
+  * Retrieves data previously set with dbus_connection_set_data().
+  * The slot must still be allocated (must not have been freed).
+  *
++ * @note This function does not take the
++ * main thread lock on DBusConnection, which allows it to be
++ * used from inside watch and timeout functions. (See the
++ * note in docs for dbus_connection_set_watch_functions().)
++ * A side effect of this is that you need to know there's
++ * a reference held on the connection while invoking
++ * dbus_connection_get_data(), or the connection could be
++ * finalized during dbus_connection_get_data().
++ *
+  * @param connection the connection
+  * @param slot the slot to get data from
+  * @returns the data, or #NULL if not found
+@@ -5803,13 +5815,13 @@
+ 
+   _dbus_return_val_if_fail (connection != NULL, NULL);
+   
+-  CONNECTION_LOCK (connection);
++  SLOTS_LOCK (connection);
+ 
+   res = _dbus_data_slot_list_get (&slot_allocator,
+                                   &connection->slot_list,
+                                   slot);
+   
+-  CONNECTION_UNLOCK (connection);
++  SLOTS_UNLOCK (connection);
+ 
+   return res;
+ }