devtmpfs: Convert dirlock to a mutex

devtmpfs has a rw_lock dirlock which serializes delete_path and
create_path.

This code was obviously never tested with the usual set of debugging
facilities enabled. In the dirlock held sections the code calls:

 - vfs functions which take mutexes
 - kmalloc(, GFP_KERNEL)

In both code pathes the might sleep warning triggers and spams dmesg.

Convert the rw_lock to a mutex. There is no reason why this needs to
be a rwlock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 50375bb8e51d..278371c7bf5a 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -32,7 +32,7 @@ static int dev_mount = 1;
 static int dev_mount;
 #endif
 
-static rwlock_t dirlock;
+static DEFINE_MUTEX(dirlock);
 
 static int __init mount_param(char *str)
 {
@@ -93,7 +93,7 @@ static int create_path(const char *nodepath)
 {
         int err;
 
-        read_lock(&dirlock);
+        mutex_lock(&dirlock);
         err = dev_mkdir(nodepath, 0755);
         if (err == -ENOENT) {
                 char *path;
@@ -117,7 +117,7 @@ static int create_path(const char *nodepath)
                 }
                 kfree(path);
         }
-        read_unlock(&dirlock);
+        mutex_unlock(&dirlock);
         return err;
 }
 
@@ -229,7 +229,7 @@ static int delete_path(const char *nodepath)
         if (!path)
                 return -ENOMEM;
 
-        write_lock(&dirlock);
+        mutex_lock(&dirlock);
         for (;;) {
                 char *base;
 
@@ -241,7 +241,7 @@ static int delete_path(const char *nodepath)
                 if (err)
                         break;
         }
-        write_unlock(&dirlock);
+        mutex_unlock(&dirlock);
 
         kfree(path);
         return err;
@@ -352,8 +352,6 @@ int __init devtmpfs_init(void)
         int err;
         struct vfsmount *mnt;
 
-        rwlock_init(&dirlock);
-
         err = register_filesystem(&dev_fs_type);
         if (err) {
                 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "