From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 19 Jul 2012 17:59:38 +0000 (-0400)
Subject: x86: mce: Serialize mce injection
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b5975917a3e5f93b5d1c95561aab0aa44327baea;p=linux-beck.git

x86: mce: Serialize mce injection

raise_mce() fiddles with global state, but lacks any kind of
serialization.

Add a mutex around the raise_mce() call, so concurrent writers do not
stomp on each other toes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---

diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c
index 753746f6dbd8..ddc72f839332 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -78,6 +78,7 @@ static void raise_exception(struct mce *m, struct pt_regs *pregs)
 }
 
 static cpumask_var_t mce_inject_cpumask;
+static DEFINE_MUTEX(mce_inject_mutex);
 
 static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
 {
@@ -229,7 +230,10 @@ static ssize_t mce_write(struct file *filp, const char __user *ubuf,
 	 * so do it a jiffie or two later everywhere.
 	 */
 	schedule_timeout(2);
+
+	mutex_lock(&mce_inject_mutex);
 	raise_mce(&m);
+	mutex_unlock(&mce_inject_mutex);
 	return usize;
 }