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-rw-r--r--fs/sysfs/dir.c22
-rw-r--r--fs/sysfs/inode.c18
-rw-r--r--fs/sysfs/sysfs.h1
3 files changed, 38 insertions, 3 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 17a819151b9..c4342a01997 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -13,14 +13,26 @@
13#include "sysfs.h" 13#include "sysfs.h"
14 14
15DECLARE_RWSEM(sysfs_rename_sem); 15DECLARE_RWSEM(sysfs_rename_sem);
16spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED;
16 17
17static void sysfs_d_iput(struct dentry * dentry, struct inode * inode) 18static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
18{ 19{
19 struct sysfs_dirent * sd = dentry->d_fsdata; 20 struct sysfs_dirent * sd = dentry->d_fsdata;
20 21
21 if (sd) { 22 if (sd) {
22 BUG_ON(sd->s_dentry != dentry); 23 /* sd->s_dentry is protected with sysfs_lock. This
23 sd->s_dentry = NULL; 24 * allows sysfs_drop_dentry() to dereference it.
25 */
26 spin_lock(&sysfs_lock);
27
28 /* The dentry might have been deleted or another
29 * lookup could have happened updating sd->s_dentry to
30 * point the new dentry. Ignore if it isn't pointing
31 * to this dentry.
32 */
33 if (sd->s_dentry == dentry)
34 sd->s_dentry = NULL;
35 spin_unlock(&sysfs_lock);
24 sysfs_put(sd); 36 sysfs_put(sd);
25 } 37 }
26 iput(inode); 38 iput(inode);
@@ -247,7 +259,10 @@ static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
247 } 259 }
248 260
249 dentry->d_fsdata = sysfs_get(sd); 261 dentry->d_fsdata = sysfs_get(sd);
262 /* protect sd->s_dentry against sysfs_d_iput */
263 spin_lock(&sysfs_lock);
250 sd->s_dentry = dentry; 264 sd->s_dentry = dentry;
265 spin_unlock(&sysfs_lock);
251 error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init); 266 error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
252 if (error) { 267 if (error) {
253 sysfs_put(sd); 268 sysfs_put(sd);
@@ -269,7 +284,10 @@ static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
269 int err = 0; 284 int err = 0;
270 285
271 dentry->d_fsdata = sysfs_get(sd); 286 dentry->d_fsdata = sysfs_get(sd);
287 /* protect sd->s_dentry against sysfs_d_iput */
288 spin_lock(&sysfs_lock);
272 sd->s_dentry = dentry; 289 sd->s_dentry = dentry;
290 spin_unlock(&sysfs_lock);
273 err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink); 291 err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
274 if (!err) { 292 if (!err) {
275 dentry->d_op = &sysfs_dentry_ops; 293 dentry->d_op = &sysfs_dentry_ops;
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 38bbe071cc1..5266eec15f6 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -246,9 +246,23 @@ static inline void orphan_all_buffers(struct inode *node)
246 */ 246 */
247void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent) 247void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
248{ 248{
249 struct dentry * dentry = sd->s_dentry; 249 struct dentry *dentry = NULL;
250 struct inode *inode; 250 struct inode *inode;
251 251
252 /* We're not holding a reference to ->s_dentry dentry but the
253 * field will stay valid as long as sysfs_lock is held.
254 */
255 spin_lock(&sysfs_lock);
256 spin_lock(&dcache_lock);
257
258 /* dget dentry if it's still alive */
259 if (sd->s_dentry && sd->s_dentry->d_inode)
260 dentry = dget_locked(sd->s_dentry);
261
262 spin_unlock(&dcache_lock);
263 spin_unlock(&sysfs_lock);
264
265 /* drop dentry */
252 if (dentry) { 266 if (dentry) {
253 spin_lock(&dcache_lock); 267 spin_lock(&dcache_lock);
254 spin_lock(&dentry->d_lock); 268 spin_lock(&dentry->d_lock);
@@ -268,6 +282,8 @@ void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
268 spin_unlock(&dentry->d_lock); 282 spin_unlock(&dentry->d_lock);
269 spin_unlock(&dcache_lock); 283 spin_unlock(&dcache_lock);
270 } 284 }
285
286 dput(dentry);
271 } 287 }
272} 288}
273 289
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 1966e1a0a01..502c949c402 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);
33extern void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent); 33extern void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent);
34extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr); 34extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
35 35
36extern spinlock_t sysfs_lock;
36extern struct rw_semaphore sysfs_rename_sem; 37extern struct rw_semaphore sysfs_rename_sem;
37extern struct super_block * sysfs_sb; 38extern struct super_block * sysfs_sb;
38extern const struct file_operations sysfs_dir_operations; 39extern const struct file_operations sysfs_dir_operations;