Messages in this thread | | | Date | Wed, 18 May 2011 20:17:56 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 03/10] ptrace: implement PTRACE_SEIZE |
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On 05/16, Tejun Heo wrote: > > @@ -315,6 +338,9 @@ static int ptrace_attach(struct task_struct *task) > if (task_is_stopped(task)) { > task->jobctl |= JOBCTL_TRAP_STOP | JOBCTL_TRAPPING; > signal_wake_up(task, 1); > + } else if (seize) { > + task->jobctl |= JOBCTL_TRAP_STOP;
So, this can race with do_signal_stop(), it can clear TRAP_STOP and JOBCTL_STOP_PENDING can guarantee the tracee will trap later.
> + * When PT_SEIZED, it's used for both group stop and explicit > + * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap > + * with accompanying siginfo. > + * > + * When !PT_SEIZED, it's used only for group stop trap with > + * CLD_STOPPED as exit_code and no siginfo. > */ > if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) { > - signr = current->jobctl & JOBCTL_STOP_SIGMASK; > - WARN_ON_ONCE(!signr); > - ptrace_stop(signr, CLD_STOPPED, 0, NULL); > - current->exit_code = 0; > + if (current->ptrace & PT_SEIZED) { > + ptrace_do_notify(SIGTRAP | PTRACE_EVENT_STOP << 8, > + CLD_STOPPED);
So. When PT_SEIZED, we always report PTRACE_EVENT_STOP and PTRACE_GET_SIGINFO always works.
Personally I agree, this looks more clean and natural.
Oleg.
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