From dd14cbc994709a1c5a64ed3621f583c49a27e521 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 11 Jun 2007 14:04:01 +0900 Subject: sysfs: fix race condition around sd->s_dentry, take#2 Allowing attribute and symlink dentries to be reclaimed means sd->s_dentry can change dynamically. However, updates to the field are unsynchronized leading to race conditions. This patch adds sysfs_lock and use it to synchronize updates to sd->s_dentry. Due to the locking around ->d_iput, the check in sysfs_drop_dentry() is complex. sysfs_lock only protect sd->s_dentry pointer itself. The validity of the dentry is protected by dcache_lock, so whether dentry is alive or not can only be tested while holding both locks. This is minimal backport of sysfs_drop_dentry() rewrite in devel branch. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/sysfs.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/sysfs/sysfs.h') diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 1966e1a0a015..502c949c402d 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -33,6 +33,7 @@ extern const unsigned char * sysfs_get_name(struct sysfs_dirent *sd); extern void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent); extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr); +extern spinlock_t sysfs_lock; extern struct rw_semaphore sysfs_rename_sem; extern struct super_block * sysfs_sb; extern const struct file_operations sysfs_dir_operations; -- cgit v1.2.3