phonedev: cdev lock_kernel() pushdown

phone_open() looks OK, but I don't trust the subsidiary drivers (and ixj in
particular).

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

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/telephony/phonedev.c b/drivers/telephony/phonedev.c
index bcea8d9b718c..4d74ba36c3a1 100644
--- a/drivers/telephony/phonedev.c
+++ b/drivers/telephony/phonedev.c
@@ -23,6 +23,7 @@
 #include <linux/errno.h>
 #include <linux/phonedev.h>
 #include <linux/init.h>
+#include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
 
@@ -53,6 +54,7 @@ static int phone_open(struct inode *inode, struct file *file)
         if (minor >= PHONE_NUM_DEVICES)
                 return -ENODEV;
 
+        lock_kernel();
         mutex_lock(&phone_lock);
         p = phone_device[minor];
         if (p)
@@ -79,6 +81,7 @@ static int phone_open(struct inode *inode, struct file *file)
         fops_put(old_fops);
 end:
         mutex_unlock(&phone_lock);
+        unlock_kernel();
         return err;
 }