From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934209AbXJLWp6 (ORCPT ); Fri, 12 Oct 2007 18:45:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932698AbXJLWVQ (ORCPT ); Fri, 12 Oct 2007 18:21:16 -0400 Received: from cantor.suse.de ([195.135.220.2]:53413 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932690AbXJLWVO (ORCPT ); Fri, 12 Oct 2007 18:21:14 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: "Eric W. Biederman" , Tejun Heo , Cornelia Huck , Greg Kroah-Hartman Subject: [PATCH 46/75] sysfs: Introduce sysfs_rename_mutex Date: Fri, 12 Oct 2007 15:16:50 -0700 Message-Id: <11922276572176-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.5.3.4 In-Reply-To: <1192227653165-git-send-email-gregkh@suse.de> References: \<20071012221251.GB4559@kroah.com\> <11922274393667-git-send-email-gregkh@suse.de> <11922274441634-git-send-email-gregkh@suse.de> <11922274503271-git-send-email-gregkh@suse.de> <11922274543490-git-send-email-gregkh@suse.de> <11922274643370-git-send-email-gregkh@suse.de> <11922274682487-git-send-email-gregkh@suse.de> <11922274732211-git-send-email-gregkh@suse.de> <11922274772578-git-send-email-gregkh@suse.de> <1192227481691-git-send-email-gregkh@suse.de> <11922274853108-git-send-email-gregkh@suse.de> <11922274901810-git-send-email-gregkh@suse.de> <11922274941588-git-send-email-gregkh@suse.de> <11922274993462-git-send-email-gregkh@suse.de> <11922275031518-git-send-email-gregkh@suse.de> <11922275074080-git-send-email-gregkh@suse.de> <11922275121763-git-send-email-gregkh@suse.de> <11922275181138-git-send-email-gregkh@suse.de> <11922275221643-git-send-email-gregkh@suse.de> <1192227527856-git-send-email-gregkh@suse.de> <11922275312531-git-send-email-gregkh@suse.de> <11922275371856-git-send-email-gregkh@suse.de> <11922275413548-git-send-email-gregkh@suse.de> <11922275462233-git-send-email-gregkh@suse.de> <1192227551156-git-send-email-gregkh@suse.de> <11922275552558-git-send-email-gregkh@suse.de> <119222756066-git-send-email-gregkh@suse.de> <11922275642378-git-send-email-gregkh@suse.de> <11922275693989-git-send-email-gregkh@suse.de> <1192227574129-git-send-email-gregkh@suse.de> <11922275781508-git-send-email-gregkh@suse.de> <11922275843236-git-send-email-gregkh@suse.de> <1192227589276-git-send-email-gregkh@suse.de> <1192227593813-git-send-email-gregkh@suse.de> <1192227598106-git-send-email-gregkh@suse.de> <1192227603335-git-send-email-gregkh@suse.de> <1192227611369-git-send-email-gregkh@suse.de> <11922276163147-git-send-email-gregkh@suse.de> <11922276201219-git-send-email-gregkh@suse.de> <11922276254051-git-send-email-gregkh@suse.de> <11922276302338-git-send-email-gregkh@suse.de> <1192227634772-git-send-email-gregkh@suse.de> <11922276392200-git-send-email-gregkh@suse.de> <11922276433594-git-send-email-gregkh@suse.de> <11922276471365-git-send-email-gregkh@suse.de> <1192227653165-git-send-email-gregkh@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Eric W. Biederman 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 Signed-off-by: Tejun Heo Cc: Cornelia Huck Signed-off-by: Greg Kroah-Hartman --- 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 1af963e..9fe83d2 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; @@ -82,7 +83,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) * 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. @@ -858,6 +859,8 @@ 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); @@ -915,6 +918,7 @@ 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; } @@ -926,6 +930,7 @@ 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; @@ -982,6 +987,7 @@ 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 16f39c3..ff93c92 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 77253aa..179e6a2 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -90,6 +90,7 @@ 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; -- 1.5.3.4