[patch 2/5] x86: mce: Serialize mce injection

[Thomas Gleixner <tglx@linutronix.de>]

[-- Attachment #1: x86-mce-serialize-mce-injection.patch --]
[-- Type: text/plain, Size: 1006 bytes --]

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>
---
 arch/x86/kernel/cpu/mcheck/mce-inject.c |    4 ++++
 1 file changed, 4 insertions(+)

Index: tip/arch/x86/kernel/cpu/mcheck/mce-inject.c
===================================================================
--- tip.orig/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ tip/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -78,6 +78,7 @@ static void raise_exception(struct mce *
 }
 
 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 *fi
 	 * 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;
 }