epoll: fix some comments

 * have an entry of this type linked to the "rbr" RB tree.

 */

struct epitem {

	/* RB-Tree node used to link this structure to the eventpoll rb-tree */

	/* RB tree node used to link this structure to the eventpoll RB tree */

	struct rb_node rbn;

	/* List header used to link this structure to the eventpoll ready list */

	/* List of ready file descriptors */

	struct list_head rdllist;

	/* RB-Tree root used to store monitored fd structs */

	/* RB tree root used to store monitored fd structs */

	struct rb_root rbr;

	/*

static struct kmem_cache *pwq_cache __read_mostly;

/* Setup the structure that is used as key for the rb-tree */

/* Setup the structure that is used as key for the RB tree */

static inline void ep_set_ffd(struct epoll_filefd *ffd,

			      struct file *file, int fd)

{

	ffd->fd = fd;

}

/* Compare rb-tree keys */

/* Compare RB tree keys */

static inline int ep_cmp_ffd(struct epoll_filefd *p1,

			     struct epoll_filefd *p2)

{

	        (p1->file < p2->file ? -1 : p1->fd - p2->fd));

}

/* Special initialization for the rb-tree node to detect linkage */

/* Special initialization for the RB tree node to detect linkage */

static inline void ep_rb_initnode(struct rb_node *n)

{

	rb_set_parent(n, n);

}

/* Removes a node from the rb-tree and marks it for a fast is-linked check */

/* Removes a node from the RB tree and marks it for a fast is-linked check */

static inline void ep_rb_erase(struct rb_node *n, struct rb_root *r)

{

	rb_erase(n, r);

	rb_set_parent(n, n);

}

/* Fast check to verify that the item is linked to the main rb-tree */

/* Fast check to verify that the item is linked to the main RB tree */

static inline int ep_rb_linked(struct rb_node *n)

{

	return rb_parent(n) != n;

	 * We don't want to get "file->f_ep_lock" because it is not

	 * necessary. It is not necessary because we're in the "struct file"

	 * cleanup path, and this means that noone is using this file anymore.

	 * So, for example, epoll_ctl() cannot hit here sicne if we reach this

	 * point, the file counter already went to zero and fget() would fail.

	 * The only hit might come from ep_free() but by holding the mutex

	 * will correctly serialize the operation. We do need to acquire

	 * "ep->mtx" after "epmutex" because ep_remove() requires it when called

	/*

	 * We need to do this because an event could have been arrived on some

	 * allocated wait queue.

	 * allocated wait queue. Note that we don't care about the ep->ovflist

	 * list, since that is used/cleaned only inside a section bound by "mtx".

	 * And ep_insert() is called with "mtx" held.

	 */

	spin_lock_irqsave(&ep->lock, flags);

	if (ep_is_linked(&epi->rdllink))

	/*

	 * If the item is "hot" and it is not registered inside the ready

	 * list, push it inside. If the item is not "hot" and it is currently

	 * registered inside the ready list, unlink it.

	 * list, push it inside.

	 */

	if (revents & event->events) {

		if (!ep_is_linked(&epi->rdllink)) {

	ep->ovflist = EP_UNACTIVE_PTR;

	/*

	 * In case of error in the event-send loop, we might still have items

	 * inside the "txlist". We need to splice them back inside ep->rdllist.

	 * In case of error in the event-send loop, or in case the number of

	 * ready events exceeds the userspace limit, we need to splice the

	 * "txlist" back inside ep->rdllist.

	 */

	list_splice(&txlist, &ep->rdllist);

	if (!list_empty(&ep->rdllist)) {

		/*

		 * Wake up (if active) both the eventpoll wait list and the ->poll()

		 * wait list.

		 * wait list (delayed after we release the lock).

		 */

		if (waitqueue_active(&ep->wq))

			__wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE |

}

/*

 * It opens an eventpoll file descriptor by suggesting a storage of "size"

 * file descriptors. The size parameter is just an hint about how to size

 * data structures. It won't prevent the user to store more than "size"

 * file descriptors inside the epoll interface. It is the kernel part of

 * the userspace epoll_create(2).

 * It opens an eventpoll file descriptor. The "size" parameter is there

 * for historical reasons, when epoll was using an hash instead of an

 * RB tree. With the current implementation, the "size" parameter is ignored

 * (besides sanity checks).

 */

asmlinkage long sys_epoll_create(int size)

{

/*

 * The following function implements the controller interface for

 * the eventpoll file that enables the insertion/removal/change of

 * file descriptors inside the interest set.  It represents

 * the kernel part of the user space epoll_ctl(2).

 * file descriptors inside the interest set.

 */

asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,

			      struct epoll_event __user *event)

	mutex_lock(&ep->mtx);

	/* Try to lookup the file inside our RB tree */

	/*

	 * Try to lookup the file inside our RB tree, Since we grabbed "mtx"

	 * above, we can be sure to be able to use the item looked up by

	 * ep_find() till we release the mutex.

	 */

	epi = ep_find(ep, tfile, fd);

	error = -EINVAL;