epoll: fix some comments (67647d0f) · Commits · e / devices / android_kernel_sony_msm8998

fs/eventpoll.c

+27 −21

Original line number	Original line	Diff line number	Diff line
	@@ -134,7 +134,7 @@ struct poll_safewake {
	* have an entry of this type linked to the "rbr" RB tree.		* have an entry of this type linked to the "rbr" RB tree.
	*/		*/
	struct epitem {		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;		struct rb_node rbn;

	/* List header used to link this structure to the eventpoll ready list */		/* List header used to link this structure to the eventpoll ready list */
	@@ -191,7 +191,7 @@ struct eventpoll {
	/* List of ready file descriptors */		/* List of ready file descriptors */
	struct list_head rdllist;		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;		struct rb_root rbr;

	/*		/*
	@@ -241,7 +241,7 @@ static struct kmem_cache *epi_cache __read_mostly;
	static struct kmem_cache *pwq_cache __read_mostly;		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,		static inline void ep_set_ffd(struct epoll_filefd *ffd,
	struct file *file, int fd)		struct file *file, int fd)
	{		{
	@@ -249,7 +249,7 @@ static inline void ep_set_ffd(struct epoll_filefd *ffd,
	ffd->fd = fd;		ffd->fd = fd;
	}		}

	/* Compare rb-tree keys */		/* Compare RB tree keys */
	static inline int ep_cmp_ffd(struct epoll_filefd *p1,		static inline int ep_cmp_ffd(struct epoll_filefd *p1,
	struct epoll_filefd *p2)		struct epoll_filefd *p2)
	{		{
	@@ -257,20 +257,20 @@ static inline int ep_cmp_ffd(struct epoll_filefd *p1,
	(p1->file < p2->file ? -1 : p1->fd - p2->fd));		(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)		static inline void ep_rb_initnode(struct rb_node *n)
	{		{
	rb_set_parent(n, 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)		static inline void ep_rb_erase(struct rb_node n, struct rb_root r)
	{		{
	rb_erase(n, r);		rb_erase(n, r);
	rb_set_parent(n, n);		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)		static inline int ep_rb_linked(struct rb_node *n)
	{		{
	return rb_parent(n) != n;		return rb_parent(n) != n;
	@@ -531,6 +531,8 @@ void eventpoll_release_file(struct file *file)
	* We don't want to get "file->f_ep_lock" because it is not		* 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"		* necessary. It is not necessary because we're in the "struct file"
	* cleanup path, and this means that noone is using this file anymore.		* 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		* The only hit might come from ep_free() but by holding the mutex
	* will correctly serialize the operation. We do need to acquire		* will correctly serialize the operation. We do need to acquire
	* "ep->mtx" after "epmutex" because ep_remove() requires it when called		* "ep->mtx" after "epmutex" because ep_remove() requires it when called
	@@ -802,7 +804,9 @@ error_unregister:

	/*		/*
	* We need to do this because an event could have been arrived on some		* 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);		spin_lock_irqsave(&ep->lock, flags);
	if (ep_is_linked(&epi->rdllink))		if (ep_is_linked(&epi->rdllink))
	@@ -845,8 +849,7 @@ static int ep_modify(struct eventpoll ep, struct epitem epi, struct epoll_even

	/*		/*
	* If the item is "hot" and it is not registered inside the ready		* 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		* list, push it inside.
	* registered inside the ready list, unlink it.
	*/		*/
	if (revents & event->events) {		if (revents & event->events) {
	if (!ep_is_linked(&epi->rdllink)) {		if (!ep_is_linked(&epi->rdllink)) {
	@@ -966,15 +969,16 @@ errxit:
	ep->ovflist = EP_UNACTIVE_PTR;		ep->ovflist = EP_UNACTIVE_PTR;

	/*		/*
	* In case of error in the event-send loop, we might still have items		* In case of error in the event-send loop, or in case the number of
	* inside the "txlist". We need to splice them back inside ep->rdllist.		* ready events exceeds the userspace limit, we need to splice the
			* "txlist" back inside ep->rdllist.
	*/		*/
	list_splice(&txlist, &ep->rdllist);		list_splice(&txlist, &ep->rdllist);

	if (!list_empty(&ep->rdllist)) {		if (!list_empty(&ep->rdllist)) {
	/*		/*
	* Wake up (if active) both the eventpoll wait list and the ->poll()		* 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))		if (waitqueue_active(&ep->wq))
	__wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE \|		__wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE \|
	@@ -1064,11 +1068,10 @@ retry:
	}		}

	/*		/*
	* It opens an eventpoll file descriptor by suggesting a storage of "size"		* It opens an eventpoll file descriptor. The "size" parameter is there
	* file descriptors. The size parameter is just an hint about how to size		* for historical reasons, when epoll was using an hash instead of an
	* data structures. It won't prevent the user to store more than "size"		* RB tree. With the current implementation, the "size" parameter is ignored
	* file descriptors inside the epoll interface. It is the kernel part of		* (besides sanity checks).
	* the userspace epoll_create(2).
	*/		*/
	asmlinkage long sys_epoll_create(int size)		asmlinkage long sys_epoll_create(int size)
	{		{
	@@ -1114,8 +1117,7 @@ error_return:
	/*		/*
	* The following function implements the controller interface for		* The following function implements the controller interface for
	* the eventpoll file that enables the insertion/removal/change of		* the eventpoll file that enables the insertion/removal/change of
	* file descriptors inside the interest set. It represents		* file descriptors inside the interest set.
	* the kernel part of the user space epoll_ctl(2).
	*/		*/
	asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,		asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,
	struct epoll_event __user *event)		struct epoll_event __user *event)
	@@ -1167,7 +1169,11 @@ asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,

	mutex_lock(&ep->mtx);		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);		epi = ep_find(ep, tfile, fd);

	error = -EINVAL;		error = -EINVAL;