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Diffstat (limited to 'kernel/watch_queue.c')
-rw-r--r--kernel/watch_queue.c58
1 files changed, 36 insertions, 22 deletions
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 2c351765c409..59ddb00d6944 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -454,6 +454,33 @@ void init_watch(struct watch *watch, struct watch_queue *wqueue)
rcu_assign_pointer(watch->queue, wqueue);
}
+static int add_one_watch(struct watch *watch, struct watch_list *wlist, struct watch_queue *wqueue)
+{
+ const struct cred *cred;
+ struct watch *w;
+
+ hlist_for_each_entry(w, &wlist->watchers, list_node) {
+ struct watch_queue *wq = rcu_access_pointer(w->queue);
+ if (wqueue == wq && watch->id == w->id)
+ return -EBUSY;
+ }
+
+ cred = current_cred();
+ if (atomic_inc_return(&cred->user->nr_watches) > task_rlimit(current, RLIMIT_NOFILE)) {
+ atomic_dec(&cred->user->nr_watches);
+ return -EAGAIN;
+ }
+
+ watch->cred = get_cred(cred);
+ rcu_assign_pointer(watch->watch_list, wlist);
+
+ kref_get(&wqueue->usage);
+ kref_get(&watch->usage);
+ hlist_add_head(&watch->queue_node, &wqueue->watches);
+ hlist_add_head_rcu(&watch->list_node, &wlist->watchers);
+ return 0;
+}
+
/**
* add_watch_to_object - Add a watch on an object to a watch list
* @watch: The watch to add
@@ -468,34 +495,21 @@ void init_watch(struct watch *watch, struct watch_queue *wqueue)
*/
int add_watch_to_object(struct watch *watch, struct watch_list *wlist)
{
- struct watch_queue *wqueue = rcu_access_pointer(watch->queue);
- struct watch *w;
-
- hlist_for_each_entry(w, &wlist->watchers, list_node) {
- struct watch_queue *wq = rcu_access_pointer(w->queue);
- if (wqueue == wq && watch->id == w->id)
- return -EBUSY;
- }
-
- watch->cred = get_current_cred();
- rcu_assign_pointer(watch->watch_list, wlist);
+ struct watch_queue *wqueue;
+ int ret = -ENOENT;
- if (atomic_inc_return(&watch->cred->user->nr_watches) >
- task_rlimit(current, RLIMIT_NOFILE)) {
- atomic_dec(&watch->cred->user->nr_watches);
- put_cred(watch->cred);
- return -EAGAIN;
- }
+ rcu_read_lock();
+ wqueue = rcu_access_pointer(watch->queue);
if (lock_wqueue(wqueue)) {
- kref_get(&wqueue->usage);
- kref_get(&watch->usage);
- hlist_add_head(&watch->queue_node, &wqueue->watches);
+ spin_lock(&wlist->lock);
+ ret = add_one_watch(watch, wlist, wqueue);
+ spin_unlock(&wlist->lock);
unlock_wqueue(wqueue);
}
- hlist_add_head_rcu(&watch->list_node, &wlist->watchers);
- return 0;
+ rcu_read_unlock();
+ return ret;
}
EXPORT_SYMBOL(add_watch_to_object);