From f63b060f455d99c3b046881803497f39c62fd3b0 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 25 Jul 2008 01:47:44 -0700
Subject: [PATCH] --- yaml --- r: 105941 b: refs/heads/master c:
 b564daf806d492dd4f7afe9b6c83b8d35d137669 h: refs/heads/master i:   105939:
 c2ea9cc879a968f1fd7979d2562e3e44fb1de445 v: v3

---
 [refs]                         |  2 +-
 trunk/fs/exec.c                |  2 ++
 trunk/include/linux/mm_types.h |  6 ++++++
 trunk/kernel/exit.c            | 15 ++++++++++++---
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 3791ff347a7c..9b2e68e679c2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9d5b327bf198d2720666de958dcc2ae219d86952
+refs/heads/master: b564daf806d492dd4f7afe9b6c83b8d35d137669
diff --git a/trunk/fs/exec.c b/trunk/fs/exec.c
index b8ee842d93cd..fe2873b8037f 100644
--- a/trunk/fs/exec.c
+++ b/trunk/fs/exec.c
@@ -1604,6 +1604,8 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
 
 	init_completion(&mm->core_done);
 	init_completion(&core_state->startup);
+	core_state->dumper.task = tsk;
+	core_state->dumper.next = NULL;
 	core_waiters = zap_threads(tsk, mm, core_state, exit_code);
 	up_write(&mm->mmap_sem);
 
diff --git a/trunk/include/linux/mm_types.h b/trunk/include/linux/mm_types.h
index ae99a28ba6ae..4d0d0abc79fe 100644
--- a/trunk/include/linux/mm_types.h
+++ b/trunk/include/linux/mm_types.h
@@ -159,8 +159,14 @@ struct vm_area_struct {
 #endif
 };
 
+struct core_thread {
+	struct task_struct *task;
+	struct core_thread *next;
+};
+
 struct core_state {
 	atomic_t nr_threads;
+	struct core_thread dumper;
 	struct completion startup;
 };
 
diff --git a/trunk/kernel/exit.c b/trunk/kernel/exit.c
index 63d82957baae..b66f0d55c791 100644
--- a/trunk/kernel/exit.c
+++ b/trunk/kernel/exit.c
@@ -664,6 +664,7 @@ void mm_update_next_owner(struct mm_struct *mm)
 static void exit_mm(struct task_struct * tsk)
 {
 	struct mm_struct *mm = tsk->mm;
+	struct core_state *core_state;
 
 	mm_release(tsk, mm);
 	if (!mm)
@@ -676,11 +677,19 @@ static void exit_mm(struct task_struct * tsk)
 	 * group with ->mm != NULL.
 	 */
 	down_read(&mm->mmap_sem);
-	if (mm->core_state) {
+	core_state = mm->core_state;
+	if (core_state) {
+		struct core_thread self;
 		up_read(&mm->mmap_sem);
 
-		if (atomic_dec_and_test(&mm->core_state->nr_threads))
-			complete(&mm->core_state->startup);
+		self.task = tsk;
+		self.next = xchg(&core_state->dumper.next, &self);
+		/*
+		 * Implies mb(), the result of xchg() must be visible
+		 * to core_state->dumper.
+		 */
+		if (atomic_dec_and_test(&core_state->nr_threads))
+			complete(&core_state->startup);
 
 		wait_for_completion(&mm->core_done);
 		down_read(&mm->mmap_sem);