kernfs_node->u.completion is used to notify deactivation completion
from kernfs_put_active() to kernfs_deactivate(). We now allow
multiple racing removals of the same node and the current removal
scheme is no longer correct - kernfs_remove() invocation may return
before the node is properly deactivated if it races against another
removal. The removal path will be restructured to address the issue.
To help such restructure which requires supporting multiple waiters,
this patch replaces kernfs_node->u.completion with
kernfs_root->deactivate_waitq. This makes deactivation event
notifications share a per-root waitqueue_head; however, the wait path
is quite cold and this will also allow shaving one pointer off
kernfs_node.
v2: Refreshed on top of ("kernfs: make kernfs_deactivate() honor
KERNFS_LOCKDEP flag").
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* This file is released under the GPLv2.
*/
* This file is released under the GPLv2.
*/
+#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/idr.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/idr.h>
*/
void kernfs_put_active(struct kernfs_node *kn)
{
*/
void kernfs_put_active(struct kernfs_node *kn)
{
+ struct kernfs_root *root = kernfs_root(kn);
int v;
if (unlikely(!kn))
int v;
if (unlikely(!kn))
if (likely(v != KN_DEACTIVATED_BIAS))
return;
if (likely(v != KN_DEACTIVATED_BIAS))
return;
- /*
- * atomic_dec_return() is a mb(), we'll always see the updated
- * kn->u.completion.
- */
- complete(kn->u.completion);
+ wake_up_all(&root->deactivate_waitq);
*/
static void kernfs_deactivate(struct kernfs_node *kn)
{
*/
static void kernfs_deactivate(struct kernfs_node *kn)
{
- DECLARE_COMPLETION_ONSTACK(wait);
- int v;
+ struct kernfs_root *root = kernfs_root(kn);
BUG_ON(!(kn->flags & KERNFS_REMOVED));
if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF))
return;
BUG_ON(!(kn->flags & KERNFS_REMOVED));
if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF))
return;
- kn->u.completion = (void *)&wait;
-
if (kn->flags & KERNFS_LOCKDEP)
rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
if (kn->flags & KERNFS_LOCKDEP)
rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
- /* atomic_add_return() is a mb(), put_active() will always see
- * the updated kn->u.completion.
- */
- v = atomic_add_return(KN_DEACTIVATED_BIAS, &kn->active);
- if (v != KN_DEACTIVATED_BIAS) {
- if (kn->flags & KERNFS_LOCKDEP)
- lock_contended(&kn->dep_map, _RET_IP_);
- wait_for_completion(&wait);
- }
+ atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
+
+ if ((kn->flags & KERNFS_LOCKDEP) &&
+ atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
+ lock_contended(&kn->dep_map, _RET_IP_);
+
+ wait_event(root->deactivate_waitq,
+ atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
if (kn->flags & KERNFS_LOCKDEP) {
lock_acquired(&kn->dep_map, _RET_IP_);
if (kn->flags & KERNFS_LOCKDEP) {
lock_acquired(&kn->dep_map, _RET_IP_);
root->dir_ops = kdops;
root->kn = kn;
root->dir_ops = kdops;
root->kn = kn;
+ init_waitqueue_head(&root->deactivate_waitq);
#include <linux/lockdep.h>
#include <linux/rbtree.h>
#include <linux/atomic.h>
#include <linux/lockdep.h>
#include <linux/rbtree.h>
#include <linux/atomic.h>
-#include <linux/completion.h>
struct file;
struct dentry;
struct file;
struct dentry;
struct rb_node rb;
union {
struct rb_node rb;
union {
- struct completion *completion;
struct kernfs_node *removed_list;
} u;
struct kernfs_node *removed_list;
} u;
/* private fields, do not use outside kernfs proper */
struct ida ino_ida;
struct kernfs_dir_ops *dir_ops;
/* private fields, do not use outside kernfs proper */
struct ida ino_ida;
struct kernfs_dir_ops *dir_ops;
+ wait_queue_head_t deactivate_waitq;
};
struct kernfs_open_file {
};
struct kernfs_open_file {