- int nwait;
- struct list_head *lsthead = &epi->pwqlist;
- struct eppoll_entry *pwq;
-
- /* This is called without locks, so we need the atomic exchange */
- nwait = xchg(&epi->nwait, 0);
-
- if (nwait) {
- while (!list_empty(lsthead)) {
- pwq = list_entry(lsthead->next, struct eppoll_entry, llink);
-
- ep_list_del(&pwq->llink);
- remove_wait_queue(pwq->whead, &pwq->wait);
- kmem_cache_free(pwq_cache, pwq);
- }
- }
-}
-
-
-/*
- * Unlink the "struct epitem" from all places it might have been hooked up.
- * This function must be called with write IRQ lock on "ep->lock".
- */
-static int ep_unlink(struct eventpoll *ep, struct epitem *epi)
-{
- int error;
-
- /*
- * It can happen that this one is called for an item already unlinked.
- * The check protect us from doing a double unlink ( crash ).
- */
- error = -ENOENT;
- if (!ep_rb_linked(&epi->rbn))
- goto eexit_1;
-
- /*
- * Clear the event mask for the unlinked item. This will avoid item
- * notifications to be sent after the unlink operation from inside
- * the kernel->userspace event transfer loop.
- */
- epi->event.events = 0;
-
- /*
- * At this point is safe to do the job, unlink the item from our rb-tree.
- * This operation togheter with the above check closes the door to
- * double unlinks.
- */
- ep_rb_erase(&epi->rbn, &ep->rbr);
-
- /*
- * If the item we are going to remove is inside the ready file descriptors
- * we want to remove it from this list to avoid stale events.
- */
- if (ep_is_linked(&epi->rdllink))
- ep_list_del(&epi->rdllink);
-
- error = 0;
-eexit_1:
-
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_unlink(%p, %p) = %d\n",
- current, ep, epi->ffd.file, error));
-
- return error;
-}
-
-
-/*
- * Removes a "struct epitem" from the eventpoll hash and deallocates
- * all the associated resources.
- */
-static int ep_remove(struct eventpoll *ep, struct epitem *epi)
-{
- int error;
- unsigned long flags;
- struct file *file = epi->ffd.file;
-
- /*
- * Removes poll wait queue hooks. We _have_ to do this without holding
- * the "ep->lock" otherwise a deadlock might occur. This because of the
- * sequence of the lock acquisition. Here we do "ep->lock" then the wait
- * queue head lock when unregistering the wait queue. The wakeup callback
- * will run by holding the wait queue head lock and will call our callback
- * that will try to get "ep->lock".
- */
- ep_unregister_pollwait(ep, epi);
-
- /* Remove the current item from the list of epoll hooks */
- spin_lock(&file->f_ep_lock);
- if (ep_is_linked(&epi->fllink))
- ep_list_del(&epi->fllink);
- spin_unlock(&file->f_ep_lock);
-
- /* We need to acquire the write IRQ lock before calling ep_unlink() */
- write_lock_irqsave(&ep->lock, flags);
-
- /* Really unlink the item from the hash */
- error = ep_unlink(ep, epi);
-
- write_unlock_irqrestore(&ep->lock, flags);
-
- if (error)
- goto eexit_1;
-
- /* At this point it is safe to free the eventpoll item */
- ep_release_epitem(epi);
-
- error = 0;
-eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p) = %d\n",
- current, ep, file, error));
-
- return error;
-}
-
-
-/*
- * This is the callback that is passed to the wait queue wakeup
- * machanism. It is called by the stored file descriptors when they
- * have events to report.
- */
-static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
-{
- int pwake = 0;