x86_64: O_EXCL on /dev/mcelog

[linux-2.6-omap-h63xx.git] / arch / x86_64 / kernel / mce.c

diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c
index f3fb8174559e43000a0a1defa029e5026c8469d7..77fee481be4fbcdb456fb83c6ea9aeaae58fb84b 100644 (file)
--- a/arch/x86_64/kernel/mce.c
+++ b/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,
 };