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authorLinus Torvalds <torvalds@linux-foundation.org>2022-02-25 14:12:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-02-25 14:12:36 -0800
commit9137eda53752ef73148e42b0d7640a00f1bc96b1 (patch)
treebf34928179776f5c5d050c5d102926a1ff82da02
parentc0419188b5c1a7735b12cf1405cafc3f8d722819 (diff)
parent84ec758fb2daa236026506868c8796b0500c047d (diff)
Merge tag 'configfs-5.17-2022-02-25' of git://git.infradead.org/users/hch/configfs
Pull configfs fix from Christoph Hellwig: - fix a race in configfs_{,un}register_subsystem (ChenXiaoSong) * tag 'configfs-5.17-2022-02-25' of git://git.infradead.org/users/hch/configfs: configfs: fix a race in configfs_{,un}register_subsystem()
-rw-r--r--fs/configfs/dir.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index d3cd2a94d1e8..d1f9d2632202 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -34,6 +34,14 @@
*/
DEFINE_SPINLOCK(configfs_dirent_lock);
+/*
+ * All of link_obj/unlink_obj/link_group/unlink_group require that
+ * subsys->su_mutex is held.
+ * But parent configfs_subsystem is NULL when config_item is root.
+ * Use this mutex when config_item is root.
+ */
+static DEFINE_MUTEX(configfs_subsystem_mutex);
+
static void configfs_d_iput(struct dentry * dentry,
struct inode * inode)
{
@@ -1859,7 +1867,9 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
group->cg_item.ci_name = group->cg_item.ci_namebuf;
sd = root->d_fsdata;
+ mutex_lock(&configfs_subsystem_mutex);
link_group(to_config_group(sd->s_element), group);
+ mutex_unlock(&configfs_subsystem_mutex);
inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
@@ -1884,7 +1894,9 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
inode_unlock(d_inode(root));
if (err) {
+ mutex_lock(&configfs_subsystem_mutex);
unlink_group(group);
+ mutex_unlock(&configfs_subsystem_mutex);
configfs_release_fs();
}
put_fragment(frag);
@@ -1931,7 +1943,9 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
dput(dentry);
+ mutex_lock(&configfs_subsystem_mutex);
unlink_group(group);
+ mutex_unlock(&configfs_subsystem_mutex);
configfs_release_fs();
}