do_jobctl_trap - take care of ptrace jobctl traps
When PT_SEIZED, it's used for both group stop and explicit SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with accompanying siginfo. If stopped, lower eight bits of exit_code contain the stop signal; otherwise, SIGTRAP.
When !PT_SEIZED, it's used only for group stop trap with stop signal number as exit_code and no siginfo.
Must be called with current->sighand->siglock held, which may be released and re-acquired before returning with intervening sleep.
|January 2017||Kernel Hackers Manual 4.8.|