From: ebiederm@xmission.com (Eric W. Biederman)
To: Greg KH <greg@kroah.com>
Cc: linux-kernel@vger.kernel.org, satyam@infradead.org,
cornelia.huck@de.ibm.com, stern@rowland.harvard.edu,
Tejun Heo <htejun@gmail.com>,
Linux Containers <containers@lists.osdl.org>,
gregkh@suse.de
Subject: [PATCH 12/25] sysfs: Introduce sysfs_rename_mutex
Date: Tue, 07 Aug 2007 15:21:06 -0600 [thread overview]
Message-ID: <m1ps1zhwhp.fsf_-_@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <m1tzrbhwkc.fsf_-_@ebiederm.dsl.xmission.com> (Eric W. Biederman's message of "Tue, 07 Aug 2007 15:19:31 -0600")
Looking carefully at the rename code we have a subtle dependency
that the structure of sysfs not change while we are performing
a rename. If the parent directory of the object we are renaming
changes while the rename is being performed nasty things could
happen when we go to release our locks.
So introduce a sysfs_rename_mutex to prevent this highly
unlikely theoretical issue.
In addition hold sysfs_rename_mutex over all calls to
sysfs_get_dentry. Allowing sysfs_get_dentry to be simplified
in the future.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/sysfs/dir.c | 8 +++++++-
fs/sysfs/file.c | 4 ++++
fs/sysfs/sysfs.h | 1 +
3 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 1078e60..e0f49b7 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -15,6 +15,7 @@
#include "sysfs.h"
DEFINE_MUTEX(sysfs_mutex);
+DEFINE_MUTEX(sysfs_rename_mutex);
spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
@@ -774,7 +775,7 @@ static struct dentry *__sysfs_get_dentry(struct super_block *sb, struct sysfs_di
* down from there looking up dentry for each step.
*
* LOCKING:
- * Kernel thread context (may sleep)
+ * mutex_lock(sysfs_rename_mutex)
*
* RETURNS:
* Pointer to found dentry on success, ERR_PTR() value on error.
@@ -859,6 +860,8 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
const char *dup_name = NULL;
int error;
+ mutex_lock(&sysfs_rename_mutex);
+
/* get the original dentry */
sd = kobj->sd;
old_dentry = sysfs_get_dentry(sd);
@@ -916,6 +919,7 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
kfree(dup_name);
dput(old_dentry);
dput(new_dentry);
+ mutex_unlock(&sysfs_rename_mutex);
return error;
}
@@ -927,6 +931,7 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
struct dentry *old_dentry = NULL, *new_dentry = NULL;
int error;
+ mutex_lock(&sysfs_rename_mutex);
BUG_ON(!sd->s_parent);
new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
@@ -983,6 +988,7 @@ again:
dput(new_parent);
dput(old_dentry);
dput(new_dentry);
+ mutex_unlock(&sysfs_rename_mutex);
return error;
}
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 416351a..fe783ea 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -470,7 +470,9 @@ int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
if (!victim_sd)
goto out;
+ mutex_lock(&sysfs_rename_mutex);
victim = sysfs_get_dentry(victim_sd);
+ mutex_unlock(&sysfs_rename_mutex);
if (IS_ERR(victim)) {
rc = PTR_ERR(victim);
victim = NULL;
@@ -509,7 +511,9 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
if (!victim_sd)
goto out;
+ mutex_lock(&sysfs_rename_mutex);
victim = sysfs_get_dentry(victim_sd);
+ mutex_unlock(&sysfs_rename_mutex);
if (IS_ERR(victim)) {
rc = PTR_ERR(victim);
victim = NULL;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 8ed13cf..791b3ed 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -89,6 +89,7 @@ extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
extern spinlock_t sysfs_assoc_lock;
extern struct mutex sysfs_mutex;
+extern struct mutex sysfs_rename_mutex;
extern struct super_block * sysfs_sb;
extern const struct file_operations sysfs_dir_operations;
extern const struct file_operations sysfs_file_operations;
--
1.5.1.1.181.g2de0
next prev parent reply other threads:[~2007-08-07 21:48 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-02 12:38 [PATCHSET 2.6.23-rc1] sysfs: locking fix and cleanups, take #2 Tejun Heo
2007-08-02 12:38 ` [PATCH 1/5] sysfs: cosmetic changes in sysfs_lookup() Tejun Heo
2007-08-02 12:38 ` [PATCH 2/5] sysfs: simplify sysfs_rename_dir() Tejun Heo
2007-08-02 12:38 ` [PATCH 4/5] sysfs: make sysfs_add_one() automatically check for duplicate entry Tejun Heo
2007-08-02 12:38 ` [PATCH 3/5] sysfs: make sysfs_add/remove_one() call link/unlink_sibling() implictly Tejun Heo
2007-08-02 12:38 ` [PATCH 5/5] sysfs: make sysfs_addrm_finish() return void Tejun Heo
2007-08-07 21:06 ` [PATCH 0/25] Sysfs cleanups & tagged directory support Eric W. Biederman
2007-08-07 21:08 ` [PATCH 01/25] sysfs: Move all of inode initialization into sysfs_init_inode Eric W. Biederman
2007-08-07 21:08 ` [PATCH 02/25] sysfs: Remove sysfs_instantiate Eric W. Biederman
2007-08-07 21:10 ` [PATCH 03/25] sysfs: Use kill_anon_super Eric W. Biederman
2007-08-07 21:11 ` [PATCH 04/25] sysfs: Make sysfs_mount static Eric W. Biederman
2007-08-07 21:12 ` [PATCH 05/25] sysfs: In sysfs_lookup don't open code sysfs_find_dirent Eric W. Biederman
2007-08-07 21:13 ` [PATCH 06/25] sysfs: Simplify readdir Eric W. Biederman
2007-08-07 21:14 ` [PATCH 07/25] sysfs: Rewrite sysfs_drop_dentry Eric W. Biederman
2007-08-07 21:16 ` [PATCH 08/25] sysfs: Implement __sysfs_get_dentry Eric W. Biederman
2007-08-07 21:17 ` [PATCH 09/25] sysfs: Move sysfs_get_dentry below __sysfs_get_dentry Eric W. Biederman
2007-08-07 21:18 ` [PATCH 10/25] sysfs: Rewrite sysfs_get_dentry in terms of __sysfs_get_dentry Eric W. Biederman
2007-08-07 21:19 ` [PATCH 11/25] sysfs: Remove s_dentry Eric W. Biederman
2007-08-07 21:21 ` Eric W. Biederman [this message]
2007-08-07 21:22 ` [PATCH 13/25] sysfs: Simply sysfs_get_dentry Eric W. Biederman
2007-08-07 21:23 ` [PATCH 14/25] sysfs: Don't use lookup_one_len_kern Eric W. Biederman
2007-08-07 21:25 ` [PATCH 15/25] vfs: Remove lookup_one_len_kern Eric W. Biederman
2007-08-07 21:26 ` [PATCH 16/25] sysfs: Support for preventing unmounts Eric W. Biederman
2007-08-07 21:27 ` [PATCH 17/25] sysfs: Rewrite rename in terms of sysfs dirents Eric W. Biederman
2007-08-07 21:28 ` [PATCH 18/25] sysfs: Rewrite sysfs_move_dir " Eric W. Biederman
2007-08-07 21:29 ` [PATCH 19/25] sysfs: sysfs_get_dentry add a sb parameter Eric W. Biederman
2007-08-07 21:31 ` [PATCH 20/25] sysfs: Rename Support multiple superblocks Eric W. Biederman
2007-08-07 21:32 ` [PATCH 21/25] sysfs: sysfs_chmod_file handle " Eric W. Biederman
2007-08-07 21:34 ` [PATCH 22/25] sysfs: sysfs_uptdate_file " Eric W. Biederman
2007-08-07 21:35 ` [PATCH 23/25] sysfs: Implement sysfs tagged directory support Eric W. Biederman
2007-08-07 21:36 ` [PATCH 24/25] sysfs: Implement sysfs_delete_link and sysfs_rename_link Eric W. Biederman
2007-08-07 21:36 ` [PATCH 25/25] driver core: Implement tagged directory support for device classes Eric W. Biederman
2007-08-08 16:31 ` alternative approached at tagged nodes Tejun Heo
2007-08-08 9:39 ` [PATCH 22/25] sysfs: sysfs_uptdate_file handle multiple superblocks Tejun Heo
2007-08-08 9:38 ` [PATCH 21/25] sysfs: sysfs_chmod_file " Tejun Heo
2007-08-08 9:35 ` [PATCH 20/25] sysfs: Rename Support " Tejun Heo
2007-08-08 15:45 ` Eric W. Biederman
2007-08-08 15:50 ` Tejun Heo
2007-08-08 16:35 ` Eric W. Biederman
2007-08-08 16:42 ` Tejun Heo
2007-08-08 16:55 ` Eric W. Biederman
2007-08-08 8:57 ` [PATCH 19/25] sysfs: sysfs_get_dentry add a sb parameter Tejun Heo
2007-08-08 15:34 ` Eric W. Biederman
2007-08-08 8:53 ` [PATCH 18/25] sysfs: Rewrite sysfs_move_dir in terms of sysfs dirents Tejun Heo
2007-08-08 8:51 ` [PATCH 17/25] sysfs: Rewrite rename " Tejun Heo
2007-08-08 15:32 ` Eric W. Biederman
2007-08-08 8:39 ` [PATCH 15/25] vfs: Remove lookup_one_len_kern Tejun Heo
2007-08-08 8:38 ` [PATCH 14/25] sysfs: Don't use lookup_one_len_kern Tejun Heo
2007-08-08 15:26 ` Eric W. Biederman
2007-08-08 15:35 ` Tejun Heo
2007-08-08 8:24 ` [PATCH 13/25] sysfs: Simply sysfs_get_dentry Tejun Heo
2007-08-08 8:19 ` [PATCH 12/25] sysfs: Introduce sysfs_rename_mutex Tejun Heo
2007-08-08 8:23 ` Tejun Heo
2007-08-08 8:28 ` Eric W. Biederman
2007-08-08 7:46 ` [PATCH 11/25] sysfs: Remove s_dentry Tejun Heo
2007-08-08 7:45 ` [PATCH 10/25] sysfs: Rewrite sysfs_get_dentry in terms of __sysfs_get_dentry Tejun Heo
2007-08-08 7:45 ` [PATCH 09/25] sysfs: Move sysfs_get_dentry below __sysfs_get_dentry Tejun Heo
2007-08-08 7:45 ` [PATCH 08/25] sysfs: Implement __sysfs_get_dentry Tejun Heo
2007-08-08 7:35 ` [PATCH 07/25] sysfs: Rewrite sysfs_drop_dentry Tejun Heo
2007-08-08 7:12 ` [PATCH 06/25] sysfs: Simplify readdir Tejun Heo
2007-08-08 6:51 ` [PATCH 05/25] sysfs: In sysfs_lookup don't open code sysfs_find_dirent Tejun Heo
2007-08-08 6:51 ` [PATCH 04/25] sysfs: Make sysfs_mount static Tejun Heo
2007-08-08 6:50 ` [PATCH 03/25] sysfs: Use kill_anon_super Tejun Heo
2007-08-08 6:37 ` [PATCH 02/25] sysfs: Remove sysfs_instantiate Tejun Heo
2007-08-08 6:37 ` [PATCH 01/25] sysfs: Move all of inode initialization into sysfs_init_inode Tejun Heo
2007-08-08 7:38 ` [PATCH 0/25] Sysfs cleanups & tagged directory support Cornelia Huck
2007-08-08 7:47 ` Eric W. Biederman
2007-08-08 7:53 ` Tejun Heo
2007-08-08 7:54 ` Cornelia Huck
2007-08-08 7:57 ` Eric W. Biederman
2007-08-08 8:37 ` Cornelia Huck
2007-08-08 8:54 ` Tejun Heo
2007-08-08 9:16 ` Cornelia Huck
2007-08-08 14:16 ` Cornelia Huck
2007-08-08 14:35 ` Tejun Heo
2007-08-08 14:50 ` Cornelia Huck
2007-08-08 14:55 ` Tejun Heo
2007-08-08 15:08 ` Eric W. Biederman
2007-08-08 15:13 ` Tejun Heo
2007-08-08 15:16 ` Tejun Heo
2007-08-08 15:53 ` Eric W. Biederman
2007-08-08 16:03 ` Tejun Heo
2007-08-08 16:37 ` Eric W. Biederman
2007-08-08 15:15 ` Cornelia Huck
2007-08-08 16:35 ` Cornelia Huck
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