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-rw-r--r--kernel/signal.c53
1 files changed, 50 insertions, 3 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 9f10b24..f65403d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1694,6 +1694,15 @@ static int sigkill_pending(struct task_struct *tsk)
}
/*
+ * Test whether the target task of the usual cldstop notification - the
+ * real_parent of @child - is in the same group as the ptracer.
+ */
+static bool real_parent_is_ptracer(struct task_struct *child)
+{
+ return same_thread_group(child->parent, child->real_parent);
+}
+
+/*
* This must be called with current->sighand->siglock held.
*
* This should be the path for all ptrace stops.
@@ -1708,6 +1717,8 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
__releases(&current->sighand->siglock)
__acquires(&current->sighand->siglock)
{
+ bool gstop_done = false;
+
if (arch_ptrace_stop_needed(exit_code, info)) {
/*
* The arch code has something special to do before a
@@ -1735,7 +1746,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
* is entered - ignore it.
*/
if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING))
- task_participate_group_stop(current);
+ gstop_done = task_participate_group_stop(current);
current->last_siginfo = info;
current->exit_code = exit_code;
@@ -1757,7 +1768,20 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
spin_unlock_irq(&current->sighand->siglock);
read_lock(&tasklist_lock);
if (may_ptrace_stop()) {
- do_notify_parent_cldstop(current, task_ptrace(current), why);
+ /*
+ * Notify parents of the stop.
+ *
+ * While ptraced, there are two parents - the ptracer and
+ * the real_parent of the group_leader. The ptracer should
+ * know about every stop while the real parent is only
+ * interested in the completion of group stop. The states
+ * for the two don't interact with each other. Notify
+ * separately unless they're gonna be duplicates.
+ */
+ do_notify_parent_cldstop(current, true, why);
+ if (gstop_done && !real_parent_is_ptracer(current))
+ do_notify_parent_cldstop(current, false, why);
+
/*
* Don't want to allow preemption here, because
* sys_ptrace() needs this task to be inactive.
@@ -1772,7 +1796,16 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
/*
* By the time we got the lock, our tracer went away.
* Don't drop the lock yet, another tracer may come.
+ *
+ * If @gstop_done, the ptracer went away between group stop
+ * completion and here. During detach, it would have set
+ * GROUP_STOP_PENDING on us and we'll re-enter TASK_STOPPED
+ * in do_signal_stop() on return, so notifying the real
+ * parent of the group stop completion is enough.
*/
+ if (gstop_done)
+ do_notify_parent_cldstop(current, false, why);
+
__set_current_state(TASK_RUNNING);
if (clear_code)
current->exit_code = 0;
@@ -2017,10 +2050,24 @@ relock:
spin_unlock_irq(&sighand->siglock);
+ /*
+ * Notify the parent that we're continuing. This event is
+ * always per-process and doesn't make whole lot of sense
+ * for ptracers, who shouldn't consume the state via
+ * wait(2) either, but, for backward compatibility, notify
+ * the ptracer of the group leader too unless it's gonna be
+ * a duplicate.
+ */
read_lock(&tasklist_lock);
+
+ do_notify_parent_cldstop(current, false, why);
+
leader = current->group_leader;
- do_notify_parent_cldstop(leader, task_ptrace(leader), why);
+ if (task_ptrace(leader) && !real_parent_is_ptracer(leader))
+ do_notify_parent_cldstop(leader, true, why);
+
read_unlock(&tasklist_lock);
+
goto relock;
}
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