Ben Chan
ab12d17bfb
When wait_for_final_state_context_complete_and_free is invoked, if the callback associated with the GSimpleAsyncResult object of the WaitForFinalStateContext object updates the modem state via mm_iface_modem_update_state, state_changed is invoked, which causes wait_for_final_state_context_complete_and_free to be invoked again on the same WaitForFinalStateContext object. That leads to the following crash, which is observed sometimes when a modem is being disabled. Thread 0 *CRASHED* ( SIGSEGV @ 0x00000000 ) 0x7fcb7728f202 [libgobject-2.0.so.0.3400.3] - gobject.c:2916 g_object_unref 0x7fcb7743205c [ModemManager] - mm-broadband-modem.c:8034 disabling_context_complete_and_free 0x7fcb77434d64 [ModemManager] - mm-broadband-modem.c:8130 disabling_wait_for_final_state_ready 0x7fcb770c0b86 [libgio-2.0.so.0.3400.3] - gsimpleasyncresult.c:775 g_simple_async_result_complete 0x7fcb7740cdbc [ModemManager] - mm-iface-modem.c:101] wait_for_final_state_context_complete_and_free 0x7fcb7740ce19 [ModemManager] - mm-iface-modem.c:128] state_changed_wait_expired 0x7fcb76f78c33 [libglib-2.0.so.0.3400.3] - gmain.c:4026] g_timeout_dispatch 0x7fcb76f78087 [libglib-2.0.so.0.3400.3] - gmain.c:2715] g_main_context_dispatch 0x7fcb76f78437 [libglib-2.0.so.0.3400.3] - gmain.c:3290] g_main_context_iterate 0x7fcb76f78891 [libglib-2.0.so.0.3400.3] - gmain.c:3484] g_main_loop_run 0x7fcb773f4d55 [ModemManager] - main.c:142] main 0x7fcb7698a9c6 [libc-2.15.so] - libc-start.c:234] __libc_start_main 0x7fcb773f48b8 [ModemManager] + 0x000218b8]
ModemManager. ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...). Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provice basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it!