mem: cdev lock_kernel() pushdown

It's really hard to tell if this is necessary - lots of weird
magic happens by way of map_devmem()

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 934ffafedaea..070e22e8ea9e 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -26,6 +26,7 @@
 #include <linux/bootmem.h>
 #include <linux/splice.h>
 #include <linux/pfn.h>
+#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -889,6 +890,9 @@ static const struct file_operations kmsg_fops = {
 
 static int memory_open(struct inode * inode, struct file * filp)
 {
+        int ret = 0;
+
+        lock_kernel();
         switch (iminor(inode)) {
                 case 1:
                         filp->f_op = &mem_fops;
@@ -932,11 +936,13 @@ static int memory_open(struct inode * inode, struct file * filp)
                         break;
 #endif
                 default:
+                        unlock_kernel();
                         return -ENXIO;
         }
         if (filp->f_op && filp->f_op->open)
-                return filp->f_op->open(inode,filp);
-        return 0;
+                ret = filp->f_op->open(inode,filp);
+        unlock_kernel();
+        return ret;
 }
 
 static const struct file_operations memory_fops = {