lkml.org 
[lkml]   [2008]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 1/3] sysfs: Remove lock ordering violation in sysfs_chmod_file.

It is a wee bit subtle but sysfs_get_dentry grabs inode->i_mutex.
of potentially all of the parents of sd. So I can not hold
the inode mutex of the directory while it is called.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/sysfs/file.c | 37 ++++++++++++++++---------------------
1 files changed, 16 insertions(+), 21 deletions(-)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 091c0de..8b572b6 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -582,7 +582,6 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
{
struct sysfs_dirent *victim_sd = NULL;
struct super_block *sb;
- struct inode * inode = NULL;
struct iattr newattrs;
int rc;

@@ -591,42 +590,38 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
if (!victim_sd)
goto out;

- rc = -ENOENT;
- mutex_lock(&sysfs_mutex);
- inode = sysfs_get_inode(victim_sd);
- mutex_unlock(&sysfs_mutex);
- if (!inode)
- goto out;
-
mutex_lock(&sysfs_rename_mutex);
sysfs_grab_supers();
- mutex_lock(&inode->i_mutex);
-
- newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
- newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
- newattrs.ia_ctime = current_fs_time(inode->i_sb);
- rc = sysfs_sd_setattr(victim_sd, inode, &newattrs);
- if (rc)
- goto out_unlock;

list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
+ struct dentry * victim;
+ struct inode * inode;
+
/* Ignore it when the dentry does not exist on the
* target superblock.
*/
- struct dentry * victim = sysfs_get_dentry(sb, victim_sd);
+ mutex_lock(&sysfs_mutex);
+ victim = sysfs_get_dentry(sb, victim_sd);
+ mutex_unlock(&sysfs_mutex);
if (IS_ERR(victim))
continue;

- fsnotify_change(victim, newattrs.ia_valid);
+ inode = victim->d_inode;
+ mutex_lock(&inode->i_mutex);
+ newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
+ newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
+ newattrs.ia_ctime = current_fs_time(inode->i_sb);
+ rc = sysfs_sd_setattr(victim_sd, inode, &newattrs);
+ if (!rc)
+ fsnotify_change(victim, newattrs.ia_valid);
+
+ mutex_unlock(&inode->i_mutex);
dput(victim);
}

- out_unlock:
- mutex_unlock(&inode->i_mutex);
sysfs_release_supers();
mutex_unlock(&sysfs_rename_mutex);
out:
- iput(inode);
sysfs_put(victim_sd);
return rc;
}
--
1.5.3.rc6.17.g1911


\
 
 \ /
  Last update: 2008-10-07 12:59    [from the cache]
©2003-2011 Jasper Spaans