aboutsummaryrefslogtreecommitdiffstats
path: root/fs/configfs
diff options
context:
space:
mode:
authorJoel Becker <joel.becker@oracle.com>2008-06-17 15:34:32 -0700
committerMark Fasheh <mfasheh@suse.com>2008-07-31 16:21:13 -0700
commit70526b67443a980d5029d9cf06903bef731a4e96 (patch)
treeaf4558619eeeda7f0075017881d8274d03854ca9 /fs/configfs
parent99cefda42ac550863b5ae1df9e60322e377decf9 (diff)
[PATCH] configfs: Pin configfs subsystems separately from new config_items.
configfs_mkdir() creates a new item by calling its parent's ->make_item/group() functions. Once that object is created, configfs_mkdir() calls try_module_get() on the new item's module. If it succeeds, the module owning the new item cannot be unloaded, and configfs is safe to reference the item. If the item and the subsystem it belongs to are part of the same module, the subsystem is also pinned. This is the common case. However, if the subsystem is made up of multiple modules, this may not pin the subsystem. Thus, it would be possible to unload the toplevel subsystem module while there is still a child item. Thus, we now try_module_get() the subsystem's module. This only really affects children of the toplevel subsystem group. Deeper children already have their parents pinned. Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Diffstat (limited to 'fs/configfs')
-rw-r--r--fs/configfs/dir.c42
1 files changed, 33 insertions, 9 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index a89058b3988..7a8db78a91d 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1100,7 +1100,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
struct configfs_subsystem *subsys;
struct configfs_dirent *sd;
struct config_item_type *type;
- struct module *owner = NULL;
+ struct module *subsys_owner = NULL, *new_item_owner = NULL;
char *name;
if (dentry->d_parent == configfs_sb->s_root) {
@@ -1137,10 +1137,25 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
goto out_put;
}
+ /*
+ * The subsystem may belong to a different module than the item
+ * being created. We don't want to safely pin the new item but
+ * fail to pin the subsystem it sits under.
+ */
+ if (!subsys->su_group.cg_item.ci_type) {
+ ret = -EINVAL;
+ goto out_put;
+ }
+ subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
+ if (!try_module_get(subsys_owner)) {
+ ret = -EINVAL;
+ goto out_put;
+ }
+
name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
if (!name) {
ret = -ENOMEM;
- goto out_put;
+ goto out_subsys_put;
}
snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
@@ -1172,7 +1187,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
* If ret != 0, then link_obj() was never called.
* There are no extra references to clean up.
*/
- goto out_put;
+ goto out_subsys_put;
}
/*
@@ -1186,8 +1201,8 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
goto out_unlink;
}
- owner = type->ct_owner;
- if (!try_module_get(owner)) {
+ new_item_owner = type->ct_owner;
+ if (!try_module_get(new_item_owner)) {
ret = -EINVAL;
goto out_unlink;
}
@@ -1236,9 +1251,13 @@ out_unlink:
mutex_unlock(&subsys->su_mutex);
if (module_got)
- module_put(owner);
+ module_put(new_item_owner);
}
+out_subsys_put:
+ if (ret)
+ module_put(subsys_owner);
+
out_put:
/*
* link_obj()/link_group() took a reference from child->parent,
@@ -1257,7 +1276,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
struct config_item *item;
struct configfs_subsystem *subsys;
struct configfs_dirent *sd;
- struct module *owner = NULL;
+ struct module *subsys_owner = NULL, *dead_item_owner = NULL;
int ret;
if (dentry->d_parent == configfs_sb->s_root)
@@ -1284,6 +1303,10 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
return -EINVAL;
}
+ /* configfs_mkdir() shouldn't have allowed this */
+ BUG_ON(!subsys->su_group.cg_item.ci_type);
+ subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
+
/*
* Ensure that no racing symlink() will make detach_prep() fail while
* the new link is temporarily attached
@@ -1321,7 +1344,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
config_item_put(parent_item);
if (item->ci_type)
- owner = item->ci_type->ct_owner;
+ dead_item_owner = item->ci_type->ct_owner;
if (sd->s_type & CONFIGFS_USET_DIR) {
configfs_detach_group(item);
@@ -1343,7 +1366,8 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
/* Drop our reference from above */
config_item_put(item);
- module_put(owner);
+ module_put(dead_item_owner);
+ module_put(subsys_owner);
return 0;
}