[PATCH] sysfs: sysfs_remove_dir() needs to invalidate the dentry

When calling sysfs_remove_dir() don't allow any further sysfs functions
to work for this kobject anymore.  This fixes a nasty USB cdc-acm oops
on disconnect.

Many thanks to Bob Copeland and Paul Fulghum for taking the time to
track this down.

Cc: Bob Copeland <email@bobcopeland.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 6 insertions, 1 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 49bd219275db..cfd290d3d6b1 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -302,6 +302,7 @@ void sysfs_remove_dir(struct kobject * kobj)
          * Drop reference from dget() on entrance.
          */
         dput(dentry);
+        kobj->dentry = NULL;
 }
 
 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 689f7bcfaf30..6beee6f6a674 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -227,12 +227,16 @@ void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
 {
         struct sysfs_dirent * sd;
-        struct sysfs_dirent * parent_sd = dir->d_fsdata;
+        struct sysfs_dirent * parent_sd;
+
+        if (!dir)
+                return;
 
         if (dir->d_inode == NULL)
                 /* no inode means this hasn't been made visible yet */
                 return;
 
+        parent_sd = dir->d_fsdata;
         mutex_lock(&dir->d_inode->i_mutex);
         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
                 if (!sd->s_element)