s390/pci: add locking for fmb access

Function measurement can be toggled at runtime. Make sure that
all access to the fmb is protected via a mutex.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index d318e38..a648338 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -7,6 +7,7 @@
 #define PCI_BAR_COUNT	6
 
 #include <linux/pci.h>
+#include <linux/mutex.h>
 #include <asm-generic/pci.h>
 #include <asm-generic/pci-dma-compat.h>
 #include <asm/pci_clp.h>
@@ -76,6 +77,7 @@
 	u8		pft;		/* pci function type */
 	u16		domain;
 
+	struct mutex lock;
 	u8 pfip[CLP_PFIP_NR_SEGMENTS];	/* pci function internal path */
 	u32 uid;			/* user defined id */
 	u8 util_str[CLP_UTIL_STR_LEN];	/* utility string */