There is a couple of subtle checks which were needed to handle ptracing from the same thread group. This was deprecated a long ago, imho this code just complicates the understanding.
And, the "->parent->signal->flags & SIGNAL_GROUP_EXIT" check in exit_notify() is not right. SIGNAL_GROUP_EXIT can mean exec(), not exit_group(). This means ptracer can lose a ptraced zombie on exec(). Minor problem, but still the bug. Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]> --- t/kernel/exit.c~PT_TG 2007-08-03 18:05:52.000000000 +0400 +++ t/kernel/exit.c 2007-08-03 21:10:40.000000000 +0400 @@ -802,7 +802,7 @@ static void exit_notify(struct task_stru __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); } - /* Let father know we died + /* Let father know we died * * Thread signals are configurable, but you aren't going to use * that to send signals to arbitary processes. @@ -815,9 +815,7 @@ static void exit_notify(struct task_stru * If our self_exec id doesn't match our parent_exec_id then * we have changed execution domain as these two values started * the same after a fork. - * */ - if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 && ( tsk->parent_exec_id != t->self_exec_id || tsk->self_exec_id != tsk->parent_exec_id) @@ -837,9 +835,7 @@ static void exit_notify(struct task_stru } state = EXIT_ZOMBIE; - if (tsk->exit_signal == -1 && - (likely(tsk->ptrace == 0) || - unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) + if (tsk->exit_signal == -1 && likely(!tsk->ptrace)) state = EXIT_DEAD; tsk->exit_state = state; --- t/kernel/signal.c~PT_TG 2007-07-28 16:58:17.000000000 +0400 +++ t/kernel/signal.c 2007-08-03 21:11:59.000000000 +0400 @@ -1561,10 +1561,6 @@ static inline int may_ptrace_stop(void) (current->ptrace & PT_ATTACHED))) return 0; - if (unlikely(current->signal == current->parent->signal) && - unlikely(current->signal->flags & SIGNAL_GROUP_EXIT)) - return 0; - /* * Are we in the middle of do_coredump? * If so and our tracer is also part of the coredump stopping - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/