coredump: move mm->core_waiters into struct core_state

Move mm->core_waiters into "struct core_state" allocated on stack.  This
shrinks mm_struct a little bit and allows further changes.

This patch mostly does s/core_waiters/core_state.  The only essential
change is that coredump_wait() must clear mm->core_state before return.

The coredump_wait()'s path is uglified and .text grows by 30 bytes, this
is fixed by the next patch.

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>

3 files changed, 7 insertions, 7 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index f7fa21dbced4..988e232254e9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -670,16 +670,16 @@ static void exit_mm(struct task_struct * tsk)
                 return;
         /*
          * Serialize with any possible pending coredump.
-         * We must hold mmap_sem around checking core_waiters
+         * We must hold mmap_sem around checking core_state
          * and clearing tsk->mm.  The core-inducing thread
-         * will increment core_waiters for each thread in the
+         * will increment ->nr_threads for each thread in the
          * group with ->mm != NULL.
          */
         down_read(&mm->mmap_sem);
-        if (mm->core_waiters) {
+        if (mm->core_state) {
                 up_read(&mm->mmap_sem);
                 down_write(&mm->mmap_sem);
-                if (!--mm->core_waiters)
+                if (!--mm->core_state->nr_threads)
                         complete(&mm->core_state->startup);
                 up_write(&mm->mmap_sem);
 
diff --git a/kernel/fork.c b/kernel/fork.c
index eeaec6893b0d..813d5c89b9d5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -400,7 +400,7 @@ static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
         INIT_LIST_HEAD(&mm->mmlist);
         mm->flags = (current->mm) ? current->mm->flags
                                   : MMF_DUMP_FILTER_DEFAULT;
-        mm->core_waiters = 0;
+        mm->core_state = NULL;
         mm->nr_ptes = 0;
         set_mm_counter(mm, file_rss, 0);
         set_mm_counter(mm, anon_rss, 0);
diff --git a/kernel/signal.c b/kernel/signal.c
index 39c1706edf03..5c7b7eaa0dc6 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1480,10 +1480,10 @@ static inline int may_ptrace_stop(void)
          * is a deadlock situation, and pointless because our tracer
          * is dead so don't allow us to stop.
          * If SIGKILL was already sent before the caller unlocked
-         * ->siglock we must see ->core_waiters != 0. Otherwise it
+         * ->siglock we must see ->core_state != NULL. Otherwise it
          * is safe to enter schedule().
          */
-        if (unlikely(current->mm->core_waiters) &&
+        if (unlikely(current->mm->core_state) &&
             unlikely(current->mm == current->parent->mm))
                 return 0;