exit: wait: cleanup the ptrace_reparented() checks

Now that EXIT_DEAD is the terminal state we can kill "int traced"
variable and check "state == EXIT_DEAD" instead to cleanup the code.  In
particular, this way it is clear that the check obviously doesn't need
tasklist_lock.

Also fix the type of "unsigned long state", "long" was always wrong
although this doesn't matter because cmpxchg/xchg uses typeof(*ptr).

[akpm@linux-foundation.org: don't make me google the C Operator Precedence table]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sterling Alexander <stalexan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 8 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 9c9526d87276..20875d6398ae 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -973,8 +973,7 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
  */
 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 {
-        unsigned long state;
-        int retval, status, traced;
+        int state, retval, status;
         pid_t pid = task_pid_vnr(p);
         uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
         struct siginfo __user *infop;
@@ -999,19 +998,18 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
                 }
                 return wait_noreap_copyout(wo, p, pid, uid, why, status);
         }
-
-        traced = ptrace_reparented(p);
         /*
          * Move the task's state to DEAD/TRACE, only one thread can do this.
          */
-        state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD;
+        state = (ptrace_reparented(p) && thread_group_leader(p)) ?
+                EXIT_TRACE : EXIT_DEAD;
         if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
                 return 0;
+
         /*
-         * It can be ptraced but not reparented, check
-         * thread_group_leader() to filter out sub-threads.
+         * Check thread_group_leader() to exclude the traced sub-threads.
          */
-        if (likely(!traced) && thread_group_leader(p)) {
+        if (state == EXIT_DEAD && thread_group_leader(p)) {
                 struct signal_struct *psig;
                 struct signal_struct *sig;
                 unsigned long maxrss;