From: Lai Siyao <lai.siyao@intel.com>
Date: Mon, 10 Oct 2016 08:44:12 +0000 (+0800)
Subject: LU-7994 statahead: add smp_mb() to serialize ops
X-Git-Tag: 2.9.54~14
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=c5c8d0623a60ee54bd11588a391b3dcd43c1abcf;p=fs%2Flustre-release.git

LU-7994 statahead: add smp_mb() to serialize ops

In ll_deauthorize_statahead(), it set thread stop flag, and then
wake up thread, however wakeup is called inside spinlock in case
ll_statahead_info is released, then we need to call smp_mb() to
serialize setting and wakeup.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: I500bdf325aa0bd122b17bea448c3b9eec809a2a7
Reviewed-on: https://review.whamcloud.com/23040
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
---

diff --git a/lustre/llite/statahead.c b/lustre/llite/statahead.c
index 3063a4e..5724ac4 100644
--- a/lustre/llite/statahead.c
+++ b/lustre/llite/statahead.c
@@ -1233,8 +1233,12 @@ void ll_deauthorize_statahead(struct inode *dir, void *key)
 		/*
 		 * statahead thread may not quit yet because it needs to cache
 		 * entries, now it's time to tell it to quit.
+		 *
+		 * In case sai is released, wake_up() is called inside spinlock,
+		 * so we have to call smp_mb() explicitely to serialize ops.
 		 */
 		thread_set_flags(&sai->sai_thread, SVC_STOPPING);
+		smp_mb();
 		wake_up(&sai->sai_thread.t_ctl_waitq);
 	}
 	spin_unlock(&lli->lli_sa_lock);