tracehook: fix exit_signal=0 case
My commit 2b2a1ff64afbadac842bbc58c5166962cf4f7664 introduced a regression
(sorry about that) for the odd case of exit_signal=0 (e.g. clone_flags=0).
This is not a normal use, but it's used by a case in the glibc test suite.
Dying with exit_signal=0 sends no signal, but it's supposed to wake up a
parent's blocked wait*() calls (unlike the delayed_group_leader case).
This fixes tracehook_notify_death() and its caller to distinguish a
"signal 0" wakeup from the delayed_group_leader case (with no wakeup).
Signed-off-by: Roland McGrath <roland@redhat.com>
Tested-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index b187558..1253283 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -493,16 +493,21 @@
* @death_cookie: value to pass to tracehook_report_death()
* @group_dead: nonzero if this was the last thread in the group to die
*
- * Return the signal number to send our parent with do_notify_parent(), or
- * zero to send no signal and leave a zombie, or -1 to self-reap right now.
+ * A return value >= 0 means call do_notify_parent() with that signal
+ * number. Negative return value can be %DEATH_REAP to self-reap right
+ * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our
+ * parent. Note that a return value of 0 means a do_notify_parent() call
+ * that sends no signal, but still wakes up a parent blocked in wait*().
*
* Called with write_lock_irq(&tasklist_lock) held.
*/
+#define DEATH_REAP -1
+#define DEATH_DELAYED_GROUP_LEADER -2
static inline int tracehook_notify_death(struct task_struct *task,
void **death_cookie, int group_dead)
{
if (task->exit_signal == -1)
- return task->ptrace ? SIGCHLD : -1;
+ return task->ptrace ? SIGCHLD : DEATH_REAP;
/*
* If something other than our normal parent is ptracing us, then
@@ -512,21 +517,21 @@
if (thread_group_empty(task) && !ptrace_reparented(task))
return task->exit_signal;
- return task->ptrace ? SIGCHLD : 0;
+ return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER;
}
/**
* tracehook_report_death - task is dead and ready to be reaped
* @task: @current task now exiting
- * @signal: signal number sent to parent, or 0 or -1
+ * @signal: return value from tracheook_notify_death()
* @death_cookie: value passed back from tracehook_notify_death()
* @group_dead: nonzero if this was the last thread in the group to die
*
* Thread has just become a zombie or is about to self-reap. If positive,
* @signal is the signal number just sent to the parent (usually %SIGCHLD).
- * If @signal is -1, this thread will self-reap. If @signal is 0, this is
- * a delayed_group_leader() zombie. The @death_cookie was passed back by
- * tracehook_notify_death().
+ * If @signal is %DEATH_REAP, this thread will self-reap. If @signal is
+ * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie.
+ * The @death_cookie was passed back by tracehook_notify_death().
*
* If normal reaping is not inhibited, @task->exit_state might be changing
* in parallel.