From 93c694645054e2a48fd522d4a7afa63d3819f482 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@cse.unsw.edu.au>
Date: Sat, 16 Apr 2005 15:26:41 -0700
Subject: [PATCH] --- yaml --- r: 198 b: refs/heads/master c:
 d28446fe2d87ea344c14741c39962dcc7aee5c78 h: refs/heads/master v: v3

---
 [refs]                |  2 +-
 trunk/drivers/md/md.c | 20 ++++++++------------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/[refs] b/[refs]
index 8dcac0a6542d..2c90e8bb858c 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 187a27845a9dc1c3da3995e24625ccf2e7a346aa
+refs/heads/master: d28446fe2d87ea344c14741c39962dcc7aee5c78
diff --git a/trunk/drivers/md/md.c b/trunk/drivers/md/md.c
index aa72c88a024f..44a164965546 100644
--- a/trunk/drivers/md/md.c
+++ b/trunk/drivers/md/md.c
@@ -2840,16 +2840,6 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
 	return thread;
 }
 
-static void md_interrupt_thread(mdk_thread_t *thread)
-{
-	if (!thread->tsk) {
-		MD_BUG();
-		return;
-	}
-	dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid);
-	send_sig(SIGKILL, thread->tsk, 1);
-}
-
 void md_unregister_thread(mdk_thread_t *thread)
 {
 	struct completion event;
@@ -2857,9 +2847,15 @@ void md_unregister_thread(mdk_thread_t *thread)
 	init_completion(&event);
 
 	thread->event = &event;
+
+	/* As soon as ->run is set to NULL, the task could disappear,
+	 * so we need to hold tasklist_lock until we have sent the signal
+	 */
+	dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid);
+	read_lock(&tasklist_lock);
 	thread->run = NULL;
-	thread->name = NULL;
-	md_interrupt_thread(thread);
+	send_sig(SIGKILL, thread->tsk, 1);
+	read_unlock(&tasklist_lock);
 	wait_for_completion(&event);
 	kfree(thread);
 }