tools headers UAPI: Sync linux/prctl.h with the kernel sources

[linux-2.6-microblaze.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 0596526..fd1c041 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1440,9 +1440,48 @@ void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
                           TASK_INTERRUPTIBLE, p);
 }
 
+static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
+                                struct task_struct *target)
+{
+       struct task_struct *parent =
+               !ptrace ? target->real_parent : target->parent;
+
+       return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
+                                    same_thread_group(current, parent));
+}
+
+/*
+ * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
+ * and tracee lists to find the target task.
+ */
+static int do_wait_pid(struct wait_opts *wo)
+{
+       bool ptrace;
+       struct task_struct *target;
+       int retval;
+
+       ptrace = false;
+       target = pid_task(wo->wo_pid, PIDTYPE_TGID);
+       if (target && is_effectively_child(wo, ptrace, target)) {
+               retval = wait_consider_task(wo, ptrace, target);
+               if (retval)
+                       return retval;
+       }
+
+       ptrace = true;
+       target = pid_task(wo->wo_pid, PIDTYPE_PID);
+       if (target && target->ptrace &&
+           is_effectively_child(wo, ptrace, target)) {
+               retval = wait_consider_task(wo, ptrace, target);
+               if (retval)
+                       return retval;
+       }
+
+       return 0;
+}
+
 static long do_wait(struct wait_opts *wo)
 {
-       struct task_struct *tsk;
        int retval;
 
        trace_sched_process_wait(wo->wo_pid);
@@ -1464,19 +1503,27 @@ repeat:
 
        set_current_state(TASK_INTERRUPTIBLE);
        read_lock(&tasklist_lock);
-       tsk = current;
-       do {
-               retval = do_wait_thread(wo, tsk);
-               if (retval)
-                       goto end;
 
-               retval = ptrace_do_wait(wo, tsk);
+       if (wo->wo_type == PIDTYPE_PID) {
+               retval = do_wait_pid(wo);
                if (retval)
                        goto end;
+       } else {
+               struct task_struct *tsk = current;
+
+               do {
+                       retval = do_wait_thread(wo, tsk);
+                       if (retval)
+                               goto end;
 
-               if (wo->wo_flags & __WNOTHREAD)
-                       break;
-       } while_each_thread(current, tsk);
+                       retval = ptrace_do_wait(wo, tsk);
+                       if (retval)
+                               goto end;
+
+                       if (wo->wo_flags & __WNOTHREAD)
+                               break;
+               } while_each_thread(current, tsk);
+       }
        read_unlock(&tasklist_lock);
 
 notask: