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Commit 7e3fb584 authored by Al Viro's avatar Al Viro
Browse files

switch epoll_ctl() to fdget 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a2e0578b

fs/eventpoll.c

+15 −16
Original line number Diff line number Diff line
@@ -1792,7 +1792,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, 
{

	int error;

	int did_lock_epmutex = 0;

	struct file *file, *tfile;

	struct fd f, tf;

	struct eventpoll *ep;

	struct epitem *epi;

	struct epoll_event epds;
@@ -1802,20 +1802,19 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, 
	    copy_from_user(&epds, event, sizeof(struct epoll_event)))

		goto error_return;



	/* Get the "struct file *" for the eventpoll file */

	error = -EBADF;

	file = fget(epfd);

	if (!file)

	f = fdget(epfd);

	if (!f.file)

		goto error_return;



	/* Get the "struct file *" for the target file */

	tfile = fget(fd);

	if (!tfile)

	tf = fdget(fd);

	if (!tf.file)

		goto error_fput;



	/* The target file descriptor must support poll */

	error = -EPERM;

	if (!tfile->f_op || !tfile->f_op->poll)

	if (!tf.file->f_op || !tf.file->f_op->poll)

		goto error_tgt_fput;



	/* Check if EPOLLWAKEUP is allowed */
@@ -1828,14 +1827,14 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, 
	 * adding an epoll file descriptor inside itself.

	 */

	error = -EINVAL;

	if (file == tfile || !is_file_epoll(file))

	if (f.file == tf.file || !is_file_epoll(f.file))

		goto error_tgt_fput;



	/*

	 * At this point it is safe to assume that the "private_data" contains

	 * our own data structure.

	 */

	ep = file->private_data;

	ep = f.file->private_data;



	/*

	 * When we insert an epoll file descriptor, inside another epoll file
@@ -1854,14 +1853,14 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, 
		did_lock_epmutex = 1;

	}

	if (op == EPOLL_CTL_ADD) {

		if (is_file_epoll(tfile)) {

		if (is_file_epoll(tf.file)) {

			error = -ELOOP;

			if (ep_loop_check(ep, tfile) != 0) {

			if (ep_loop_check(ep, tf.file) != 0) {

				clear_tfile_check_list();

				goto error_tgt_fput;

			}

		} else

			list_add(&tfile->f_tfile_llink, &tfile_check_list);

			list_add(&tf.file->f_tfile_llink, &tfile_check_list);

	}



	mutex_lock_nested(&ep->mtx, 0);
@@ -1871,14 +1870,14 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, 
	 * 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, tf.file, fd);



	error = -EINVAL;

	switch (op) {

	case EPOLL_CTL_ADD:

		if (!epi) {

			epds.events |= POLLERR | POLLHUP;

			error = ep_insert(ep, &epds, tfile, fd);

			error = ep_insert(ep, &epds, tf.file, fd);

		} else

			error = -EEXIST;

		clear_tfile_check_list();
@@ -1903,9 +1902,9 @@ error_tgt_fput: 
	if (did_lock_epmutex)

		mutex_unlock(&epmutex);



	fput(tfile);

	fdput(tf);

error_fput:

	fput(file);

	fdput(f);

error_return:



	return error;