coredump: simplify core_state->nr_threads calculation

Change zap_process() to return int instead of incrementing
mm->core_state->nr_threads directly.  Change zap_threads() to set
mm->core_state only on success.

This patch restores the original size of .text, and more importantly now
->nr_threads is used in two places only.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 17 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 50de3aaff4d0..c74bb34eeeff 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1502,9 +1502,10 @@ out:
         return ispipe;
 }
 
-static void zap_process(struct task_struct *start)
+static int zap_process(struct task_struct *start)
 {
         struct task_struct *t;
+        int nr = 0;
 
         start->signal->flags = SIGNAL_GROUP_EXIT;
         start->signal->group_stop_count = 0;
@@ -1512,31 +1513,33 @@ static void zap_process(struct task_struct *start)
         t = start;
         do {
                 if (t != current && t->mm) {
-                        t->mm->core_state->nr_threads++;
                         sigaddset(&t->pending.signal, SIGKILL);
                         signal_wake_up(t, 1);
+                        nr++;
                 }
         } while_each_thread(start, t);
+
+        return nr;
 }
 
 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
-                                int exit_code)
+                                struct core_state *core_state, int exit_code)
 {
         struct task_struct *g, *p;
         unsigned long flags;
-        int err = -EAGAIN;
+        int nr = -EAGAIN;
 
         spin_lock_irq(&tsk->sighand->siglock);
         if (!signal_group_exit(tsk->signal)) {
+                mm->core_state = core_state;
                 tsk->signal->group_exit_code = exit_code;
-                zap_process(tsk);
-                err = 0;
+                nr = zap_process(tsk);
         }
         spin_unlock_irq(&tsk->sighand->siglock);
-        if (err)
-                return err;
+        if (unlikely(nr < 0))
+                return nr;
 
-        if (atomic_read(&mm->mm_users) == mm->core_state->nr_threads + 1)
+        if (atomic_read(&mm->mm_users) == nr + 1)
                 goto done;
         /*
          * We should find and kill all tasks which use this mm, and we should
@@ -1579,7 +1582,7 @@ static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
                         if (p->mm) {
                                 if (unlikely(p->mm == mm)) {
                                         lock_task_sighand(p, &flags);
-                                        zap_process(p);
+                                        nr += zap_process(p);
                                         unlock_task_sighand(p, &flags);
                                 }
                                 break;
@@ -1588,7 +1591,8 @@ static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
         }
         rcu_read_unlock();
 done:
-        return mm->core_state->nr_threads;
+        core_state->nr_threads = nr;
+        return nr;
 }
 
 static int coredump_wait(int exit_code)
@@ -1601,12 +1605,7 @@ static int coredump_wait(int exit_code)
 
         init_completion(&mm->core_done);
         init_completion(&core_state.startup);
-        core_state.nr_threads = 0;
-        mm->core_state = &core_state;
-
-        core_waiters = zap_threads(tsk, mm, exit_code);
-        if (core_waiters < 0)
-                mm->core_state = NULL;
+        core_waiters = zap_threads(tsk, mm, &core_state, exit_code);
         up_write(&mm->mmap_sem);
 
         if (unlikely(core_waiters < 0))