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authorTejun Heo <htejun@gmail.com>2007-06-11 14:04:01 +0900
committerGreg Kroah-Hartman <gregkh@suse.de>2007-06-12 16:08:47 -0700
commitdd14cbc994709a1c5a64ed3621f583c49a27e521 (patch)
treee48d38b7450661907c7b75490504c7f70b04d6cc /fs/sysfs/sysfs.h
parent6aa054aadfea613a437ad0b15d38eca2b963fc0a (diff)
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 <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/sysfs/sysfs.h')
-rw-r--r--fs/sysfs/sysfs.h1
1 files changed, 1 insertions, 0 deletions
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;