Kernel panic on invalid phone hang-up

[Lenka Trochtova]

The following code executed by a task causes the kernel to panic:

   ipcarg_t phone = -1;
   ipc_hangup(phone);

The kconsole error message states:

Kernel panic in _mutex_lock_timeout() at generic/src/synch/mutex.c:74: Assertion failed (mtx→type = MUTEX_ACTIVE), caller=0x8012fd86.
cpu0: halted

The problem was observed on ia32 qemu machine, but it might be more generic.

[Jakub Jermář]

Fixed in changeset:head,356.