Commit 773318ed authored by Al Viro's avatar Al Viro
Browse files

untangling ep_call_nested(): and there was much rejoicing 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 99d84d43

fs/eventpoll.c

+11 −32
Original line number Diff line number Diff line
@@ -439,25 +439,6 @@ static bool ep_push_nested(void *cookie) 
	return true;

}



/**

 * ep_call_nested - Perform a bound (possibly) nested call, by checking

 *                  that the recursion limit is not exceeded, and that

 *                  the same nested call (by the meaning of same cookie) is

 *                  no re-entered.

 *

 * @nproc: Nested call core function pointer.

 * @priv: Opaque data to be passed to the @nproc callback.

 * @cookie: Cookie to be used to identify this nested call.

 *

 * Returns: Returns the code returned by the @nproc callback, or -1 if

 *          the maximum recursion limit has been exceeded.

 */

static int ep_call_nested(int (*nproc)(void *, void *, int), void *priv,

			  void *cookie)

{

	return (*nproc)(priv, cookie, nesting);

}



/*

 * As described in commit 0ccf831cb lockdep: annotate epoll

 * the use of wait queues used by epoll is done in a very controlled
@@ -1325,7 +1306,7 @@ static void path_count_init(void) 
		path_count[i] = 0;

}



static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)

static int reverse_path_check_proc(void *priv, void *cookie, int depth)

{

	int error = 0;

	struct file *file = priv;
@@ -1341,13 +1322,13 @@ static int reverse_path_check_proc(void *priv, void *cookie, int call_nests) 
		child_file = epi->ep->file;

		if (is_file_epoll(child_file)) {

			if (list_empty(&child_file->f_ep_links)) {

				if (path_count_inc(call_nests)) {

				if (path_count_inc(depth)) {

					error = -1;

					break;

				}

			} else {

				error = ep_call_nested(reverse_path_check_proc,

							child_file, child_file);

				error = reverse_path_check_proc(child_file, child_file,

								depth + 1);

			}

			if (error != 0)

				break;
@@ -1379,8 +1360,7 @@ static int reverse_path_check(void) 
	/* let's call this for all tfiles */

	list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {

		path_count_init();

		error = ep_call_nested(reverse_path_check_proc, current_file,

					current_file);

		error = reverse_path_check_proc(current_file, current_file, 0);

		if (error)

			break;

	}
@@ -1886,8 +1866,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, 
}



/**

 * ep_loop_check_proc - Callback function to be passed to the @ep_call_nested()

 *                      API, to verify that adding an epoll file inside another

 * ep_loop_check_proc - verify that adding an epoll file inside another

 *                      epoll structure, does not violate the constraints, in

 *                      terms of closed loops, or too deep chains (which can

 *                      result in excessive stack usage).
@@ -1900,7 +1879,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, 
 * Returns: Returns zero if adding the epoll @file inside current epoll

 *          structure @ep does not violate the constraints, or -1 otherwise.

 */

static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)

static int ep_loop_check_proc(void *priv, void *cookie, int depth)

{

	int error = 0;

	struct file *file = priv;
@@ -1912,7 +1891,7 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) 
	if (!ep_push_nested(cookie)) /* limits recursion */

		return -1;



	mutex_lock_nested(&ep->mtx, call_nests + 1);

	mutex_lock_nested(&ep->mtx, depth + 1);

	ep->gen = loop_check_gen;

	for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {

		epi = rb_entry(rbp, struct epitem, rbn);
@@ -1920,8 +1899,8 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) 
			ep_tovisit = epi->ffd.file->private_data;

			if (ep_tovisit->gen == loop_check_gen)

				continue;

			error = ep_call_nested(ep_loop_check_proc, epi->ffd.file,

					ep_tovisit);

			error = ep_loop_check_proc(epi->ffd.file, ep_tovisit,

						   depth + 1);

			if (error != 0)

				break;

		} else {
@@ -1959,7 +1938,7 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) 
 */

static int ep_loop_check(struct eventpoll *ep, struct file *file)

{

	return ep_call_nested(ep_loop_check_proc, file, ep);

	return ep_loop_check_proc(file, ep, 0);

}



static void clear_tfile_check_list(void)