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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>
This commit is contained in:
Kay Sievers 2009-10-28 19:51:06 +01:00 committed by Greg Kroah-Hartman
parent 0092699643
commit ed413ae6e7
1 changed files with 16 additions and 10 deletions
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26
drivers/base/devtmpfs.c
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@ -32,6 +32,8 @@ static int dev_mount = 1;
static int dev_mount; static int dev_mount;
#endif #endif
static rwlock_t dirlock;
static int __init mount_param(char *str) static int __init mount_param(char *str)
{ {
dev_mount = simple_strtoul(str, NULL, 0); dev_mount = simple_strtoul(str, NULL, 0);
@ -86,16 +88,12 @@ static int dev_mkdir(const char *name, mode_t mode)
static int create_path(const char *nodepath) static int create_path(const char *nodepath)
{ {
char *path;
struct nameidata nd; struct nameidata nd;
int err = 0; int err = 0;
path = kstrdup(nodepath, GFP_KERNEL); read_lock(&dirlock);
if (!path)
return -ENOMEM;
err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
path, LOOKUP_PARENT, &nd); nodepath, LOOKUP_PARENT, &nd);
if (err == 0) { if (err == 0) {
struct dentry *dentry; struct dentry *dentry;
@ -107,14 +105,17 @@ static int create_path(const char *nodepath)
dput(dentry); dput(dentry);
} }
mutex_unlock(&nd.path.dentry->d_inode->i_mutex); mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path); path_put(&nd.path);
} else if (err == -ENOENT) { } else if (err == -ENOENT) {
char *path;
char *s; char *s;
/* parent directories do not exist, create them */ /* parent directories do not exist, create them */
path = kstrdup(nodepath, GFP_KERNEL);
if (!path)
return -ENOMEM;
s = path; s = path;
while (1) { for (;;) {
s = strchr(s, '/'); s = strchr(s, '/');
if (!s) if (!s)
break; break;
@ -125,9 +126,10 @@ static int create_path(const char *nodepath)
s[0] = '/'; s[0] = '/';
s++; s++;
} }
kfree(path);
} }
read_unlock(&dirlock);
kfree(path);
return err; return err;
} }
@ -234,7 +236,8 @@ static int delete_path(const char *nodepath)
if (!path) if (!path)
return -ENOMEM; return -ENOMEM;
while (1) { write_lock(&dirlock);
for (;;) {
char *base; char *base;
base = strrchr(path, '/'); base = strrchr(path, '/');
@ -245,6 +248,7 @@ static int delete_path(const char *nodepath)
if (err) if (err)
break; break;
} }
write_unlock(&dirlock);
kfree(path); kfree(path);
return err; return err;
@ -360,6 +364,8 @@ int __init devtmpfs_init(void)
int err; int err;
struct vfsmount *mnt; struct vfsmount *mnt;
rwlock_init(&dirlock);
err = register_filesystem(&dev_fs_type); err = register_filesystem(&dev_fs_type);
if (err) { if (err) {
printk(KERN_ERR "devtmpfs: unable to register devtmpfs " printk(KERN_ERR "devtmpfs: unable to register devtmpfs "