port-serial: force-close the port if reopen fails

If the reopening operation fails when attempting to recover the
previous open count, it could mean the port is already gone. We didn't
get a HUP in the TTY because the channel I/O monitoring isn't in place
during this time, so this is the best way to detect that at this
point.

And if we do see an error, we'll flag the port as forced closed so
that we do not attempt to reopen it again.

  ModemManager[4219]: <debug> [1568123246.421399] Disconnecting bearer '/org/freedesktop/ModemManager1/Bearer/0'
  ModemManager[4219]: <info>  [1568123246.421465] Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connected -> disconnecting)
  ModemManager[4219]: <debug> [1568123246.421698] Reopening data port (modemu)...
  ModemManager[4219]: <debug> [1568123246.421722] (modemu) reopening port (2)
  ModemManager[4219]: <debug> [1568123246.421740] (modemu) device open count is 1 (close)
  ModemManager[4219]: <debug> [1568123246.421754] (modemu) device open count is 0 (close)
  ModemManager[4219]: <debug> [1568123246.421770] (modemu) closing serial port...
  ModemManager[4219]: <debug> [1568123246.421786] (modemu): port now disconnected
  ModemManager[4219]: <debug> [1568123246.421816] (modemu) serial port closed
  ModemManager[4219]: <info>  [1568123248.028573] (tty/modemu): released by device '/sys/devices/pci0000:00/0000:00:00.0'
  ModemManager[4219]: <debug> [1568123248.028637] Removing empty device '/sys/devices/pci0000:00/0000:00:00.0'
  ModemManager[4219]: <debug> [1568123248.028866] Removing from DBus bearer at '/org/freedesktop/ModemManager1/Bearer/0'
  ModemManager[4219]: <debug> [1568123248.028914] [device /sys/devices/pci0000:00/0000:00:00.0] unexported modem from path '/org/freedesktop/ModemManager1/Modem/0'
  ModemManager[4219]: <debug> [1568123248.028944] Periodic signal checks disabled
  ModemManager[4219]: <debug> [1568123256.401738] Connection monitoring is unsupported by the device
  ModemManager[4219]: <debug> [1568123256.422939] (modemu) opening serial port...
  ModemManager[4219]: <warn>  [1568123256.423062] (modemu) could not open serial device (2)
  ModemManager[4219]: <debug> [1568123256.423104] Couldn't disconnect bearer '/org/freedesktop/ModemManager1/Bearer/0': Couldn't reopen port (0): Could not open serial device modemu: No such file or directory
  ModemManager[4219]: _close_internal: assertion 'self->priv->open_count > 0' failed

  Thread 1 "ModemManager" received signal SIGTRAP, Trace/breakpoint trap.
  0x00007ffff77894e6 in ?? () from /usr/lib/libglib-2.0.so.0
  (gdb)
  (gdb) bt
  #0  0x00007ffff77894e6 in  () at /usr/lib/libglib-2.0.so.0
  #1  0x00007ffff7789738 in g_logv () at /usr/lib/libglib-2.0.so.0
  #2  0x00007ffff777ff80 in g_log () at /usr/lib/libglib-2.0.so.0
  #3  0x0000555555661115 in _close_internal (self=0x555555796380, force=0) at mm-port-serial.c:1378
  #4  0x0000555555661865 in mm_port_serial_close (self=0x555555796380) at mm-port-serial.c:1503
  #5  0x00005555556078cc in ports_context_unref (ctx=0x5555557c4ca0) at mm-broadband-modem.c:9801
  #6  0x000055555560e33a in finalize (object=0x5555557a4250) at mm-broadband-modem.c:11940
  #7  0x00007ffff787b351 in g_object_unref () at /usr/lib/libgobject-2.0.so.0
  #8  0x00005555555b1c71 in detailed_disconnect_context_free (ctx=0x555555785000) at mm-broadband-bearer.c:1369
  #9  0x00007ffff795d62a in  () at /usr/lib/libgio-2.0.so.0
  #10 0x00007ffff787b351 in g_object_unref () at /usr/lib/libgobject-2.0.so.0
  #11 0x00005555555b2532 in data_reopen_3gpp_ready (data=0x555555796380, res=0x55555573a580, task=0x55555573a040) at mm-broadband-bearer.c:1605
  #12 0x00007ffff795d584 in  () at /usr/lib/libgio-2.0.so.0
  #13 0x00007ffff7962a87 in  () at /usr/lib/libgio-2.0.so.0
  #14 0x0000555555661bc6 in reopen_do (self=0x555555796380) at mm-port-serial.c:1607
  #15 0x00007ffff778e3c4 in  () at /usr/lib/libglib-2.0.so.0
  #16 0x00007ffff778ebb0 in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
  #17 0x00007ffff7790b11 in  () at /usr/lib/libglib-2.0.so.0
  #18 0x00007ffff7791a63 in g_main_loop_run () at /usr/lib/libglib-2.0.so.0
  #19 0x000055555559afb0 in main (argc=3, argv=0x7fffffffea58) at main.c:181

1 files changed, 11 insertions, 2 deletions

diff --git a/src/mm-port-serial.c b/src/mm-port-serial.c
index bd3b92a7..052d0dd8 100644
--- a/src/mm-port-serial.c
+++ b/src/mm-port-serial.c
@@ -1596,9 +1596,18 @@ reopen_do (MMPortSerial *self)
         }
     }
 
-    if (error)
+    if (error) {
+        /* An error during port reopening may mean that the device is
+         * already gone. Note that we won't get a HUP in the TTY when
+         * the port is gone during the reopen wait time, because there's
+         * no channel I/O monitoring in place.
+         *
+         * If we ever see this, we'll flag the port as forced close right
+         * away, because the open count would anyway be broken afterwards.
+         */
+        port_serial_close_force (self);
         g_task_return_error (task, error);
-    else
+    } else
         g_task_return_boolean (task, TRUE);
     g_object_unref (task);