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>

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 50375bb..278371c 100644 (file)
--- 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 "