Driver core: devtmpfs: prevent concurrent subdirectory creation and removal
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 48526b9..1cf498f 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -32,6 +32,8 @@
static int dev_mount;
#endif
+static rwlock_t dirlock;
+
static int __init mount_param(char *str)
{
dev_mount = simple_strtoul(str, NULL, 0);
@@ -86,16 +88,12 @@
static int create_path(const char *nodepath)
{
- char *path;
struct nameidata nd;
int err = 0;
- path = kstrdup(nodepath, GFP_KERNEL);
- if (!path)
- return -ENOMEM;
-
+ read_lock(&dirlock);
err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
- path, LOOKUP_PARENT, &nd);
+ nodepath, LOOKUP_PARENT, &nd);
if (err == 0) {
struct dentry *dentry;
@@ -107,14 +105,17 @@
dput(dentry);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-
path_put(&nd.path);
} else if (err == -ENOENT) {
+ char *path;
char *s;
/* parent directories do not exist, create them */
+ path = kstrdup(nodepath, GFP_KERNEL);
+ if (!path)
+ return -ENOMEM;
s = path;
- while (1) {
+ for (;;) {
s = strchr(s, '/');
if (!s)
break;
@@ -125,9 +126,10 @@
s[0] = '/';
s++;
}
+ kfree(path);
}
+ read_unlock(&dirlock);
- kfree(path);
return err;
}
@@ -234,7 +236,8 @@
if (!path)
return -ENOMEM;
- while (1) {
+ write_lock(&dirlock);
+ for (;;) {
char *base;
base = strrchr(path, '/');
@@ -245,6 +248,7 @@
if (err)
break;
}
+ write_unlock(&dirlock);
kfree(path);
return err;
@@ -360,6 +364,8 @@
int err;
struct vfsmount *mnt;
+ rwlock_init(&dirlock);
+
err = register_filesystem(&dev_fs_type);
if (err) {
printk(KERN_ERR "devtmpfs: unable to register devtmpfs "