Messages in this thread | | | Date | Thu, 16 Oct 2008 18:57:27 +0200 | From | Oleg Nesterov <> | Subject | Re: SIGTRAP vs. sys_exit_group race |
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Roland, what do you think?
On 10/06, Jan Kiszka wrote: > > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -1528,10 +1528,11 @@ static void ptrace_stop(int exit_code, i > spin_unlock_irq(¤t->sighand->siglock); > arch_ptrace_stop(exit_code, info); > spin_lock_irq(¤t->sighand->siglock); > - if (sigkill_pending(current)) > - return; > } > > + if (sigkill_pending(current)) > + return; > +
Personally, I think this change is good anyway. The tracee shouldn't sleep in TASK_TRACED with the pending SIGKILL.
And the current code is confusing, imho. Why do we check sigkill_pending() under arch_ptrace_stop_needed() ? Yes, it unlocks ->siglock and can sleep, so SIGKILL can come in between. But it is quite possible that SIGKILL is already pending when we enter ptrace_stop().
The only problem I can see this patch adds a user-visible change, even if this change looks good to me. For example, if we send SIGKILL to the thread group, the tracee will not send PTRACE_EVENT_EXIT.
I think we need further changes. If the thread group group was killed by some fatal signal (but not SIGKILL) the tracee will sleep with SIGNAL_GROUP_EXIT, this is not nice too. But imho the patch makes sense anyway.
Oleg.
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