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>

1 files changed, 2 insertions, 2 deletions

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;