From 5a544405fc62e362308642a872a627be3be9d997 Mon Sep 17 00:00:00 2001
From: Tim Hockin <thockin@google.com>
Date: Sat, 21 Jul 2007 17:10:35 +0200
Subject: [PATCH] --- yaml --- r: 62391 b: refs/heads/master c:
 f528e7ba28492e363a64c80c414ded4cadf48f89 h: refs/heads/master i:   62389:
 37ebdb960b897a5817eeba2de73c2162c78e719b   62387:
 55d5e50e5df2b75c4e9d3978d029b33597faea0d   62383:
 66461cfbd9b476979c97195855f0f4d1fb1c213c v: v3

---
 [refs]                         |  2 +-
 trunk/arch/x86_64/kernel/mce.c | 36 ++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 232f55ab1e51..0d7a0c5eeefc 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a5ba7971045a90a36cef8f7d5a3075600b475b74
+refs/heads/master: f528e7ba28492e363a64c80c414ded4cadf48f89
diff --git a/trunk/arch/x86_64/kernel/mce.c b/trunk/arch/x86_64/kernel/mce.c
index f3fb8174559e..77fee481be4f 100644
--- a/trunk/arch/x86_64/kernel/mce.c
+++ b/trunk/arch/x86_64/kernel/mce.c
@@ -465,6 +465,40 @@ void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
  * Character device to read and clear the MCE log.
  */
 
+static DEFINE_SPINLOCK(mce_state_lock);
+static int open_count;	/* #times opened */
+static int open_exclu;	/* already open exclusive? */
+
+static int mce_open(struct inode *inode, struct file *file)
+{
+	spin_lock(&mce_state_lock);
+
+	if (open_exclu || (open_count && (file->f_flags & O_EXCL))) {
+		spin_unlock(&mce_state_lock);
+		return -EBUSY;
+	}
+
+	if (file->f_flags & O_EXCL)
+		open_exclu = 1;
+	open_count++;
+
+	spin_unlock(&mce_state_lock);
+
+	return 0;
+}
+
+static int mce_release(struct inode *inode, struct file *file)
+{
+	spin_lock(&mce_state_lock);
+
+	open_count--;
+	open_exclu = 0;
+
+	spin_unlock(&mce_state_lock);
+
+	return 0;
+}
+
 static void collect_tscs(void *data) 
 { 
 	unsigned long *cpu_tsc = (unsigned long *)data;
@@ -555,6 +589,8 @@ static int mce_ioctl(struct inode *i, struct file *f,unsigned int cmd, unsigned
 }
 
 static const struct file_operations mce_chrdev_ops = {
+	.open = mce_open,
+	.release = mce_release,
 	.read = mce_read,
 	.ioctl = mce_ioctl,
 };