job control: Add @for_ptrace to do_notify_parent_cldstop()

Currently, do_notify_parent_cldstop() determines whether the
notification is for the real parent or ptracer.  Move the decision to
the caller by adding @for_ptrace parameter to
do_notify_parent_cldstop().  All the callers are updated to pass
task_ptrace(target_task), so this patch doesn't cause any behavior
difference.

While at it, add function comment to do_notify_parent_cldstop().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>

1 files changed, 24 insertions, 7 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 2f2c8f6ee01f..69d60540a680 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1595,16 +1595,30 @@ int do_notify_parent(struct task_struct *tsk, int sig)
         return ret;
 }
 
-static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
+/**
+ * do_notify_parent_cldstop - notify parent of stopped/continued state change
+ * @tsk: task reporting the state change
+ * @for_ptracer: the notification is for ptracer
+ * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
+ *
+ * Notify @tsk's parent that the stopped/continued state has changed.  If
+ * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
+ * If %true, @tsk reports to @tsk->parent which should be the ptracer.
+ *
+ * CONTEXT:
+ * Must be called with tasklist_lock at least read locked.
+ */
+static void do_notify_parent_cldstop(struct task_struct *tsk,
+                                     bool for_ptracer, int why)
 {
         struct siginfo info;
         unsigned long flags;
         struct task_struct *parent;
         struct sighand_struct *sighand;
 
-        if (task_ptrace(tsk))
+        if (for_ptracer) {
                 parent = tsk->parent;
-        else {
+        } else {
                 tsk = tsk->group_leader;
                 parent = tsk->real_parent;
         }
@@ -1743,7 +1757,7 @@ 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, why);
+                do_notify_parent_cldstop(current, task_ptrace(current), why);
                 /*
                  * Don't want to allow preemption here, because
                  * sys_ptrace() needs this task to be inactive.
@@ -1886,7 +1900,8 @@ retry:
 
                 if (notify) {
                         read_lock(&tasklist_lock);
-                        do_notify_parent_cldstop(current, notify);
+                        do_notify_parent_cldstop(current, task_ptrace(current),
+                                                 notify);
                         read_unlock(&tasklist_lock);
                 }
 
@@ -1982,6 +1997,7 @@ relock:
          * the CLD_ si_code into SIGNAL_CLD_MASK bits.
          */
         if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
+                struct task_struct *leader;
                 int why;
 
                 if (signal->flags & SIGNAL_CLD_CONTINUED)
@@ -1994,7 +2010,8 @@ relock:
                 spin_unlock_irq(&sighand->siglock);
 
                 read_lock(&tasklist_lock);
-                do_notify_parent_cldstop(current->group_leader, why);
+                leader = current->group_leader;
+                do_notify_parent_cldstop(leader, task_ptrace(leader), why);
                 read_unlock(&tasklist_lock);
                 goto relock;
         }
@@ -2167,7 +2184,7 @@ out:
 
         if (unlikely(group_stop)) {
                 read_lock(&tasklist_lock);
-                do_notify_parent_cldstop(tsk, group_stop);
+                do_notify_parent_cldstop(tsk, task_ptrace(tsk), group_stop);
                 read_unlock(&tasklist_lock);
         }
 }