Commit 6a3890c4 authored by Al Viro's avatar Al Viro
Browse files

get rid of ep_push_nested() 



The only remaining user is loop checking.  But there we only need
to check that we have not walked into the epoll we are inserting
into - we are adding an edge to acyclic graph, so any loop being
created will have to pass through the source of that edge.

So we don't need that array of cookies - we have only one eventpoll
to watch out for.  RIP ep_push_nested(), along with the cookies
array.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 56c428ca

fs/eventpoll.c

+4 −25
Original line number Diff line number Diff line
@@ -254,8 +254,7 @@ static DEFINE_MUTEX(epmutex); 
static u64 loop_check_gen = 0;



/* Used to check for epoll file descriptor inclusion loops */

static void *cookies[EP_MAX_NESTS + 1];

static int nesting;

static struct eventpoll *inserting_into;



/* Slab cache used to allocate "struct epitem" */

static struct kmem_cache *epi_cache __read_mostly;
@@ -424,21 +423,6 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi) 


#endif /* CONFIG_NET_RX_BUSY_POLL */



static bool ep_push_nested(void *cookie)

{

	int i;



	if (nesting > EP_MAX_NESTS) /* too deep nesting */

		return false;



	for (i = 0; i < nesting; i++) {

		if (cookies[i] == cookie) /* loop detected */

			return false;

	}

	cookies[nesting++] = cookie;

	return true;

}



/*

 * As described in commit 0ccf831cb lockdep: annotate epoll

 * the use of wait queues used by epoll is done in a very controlled
@@ -1885,12 +1869,11 @@ static int ep_loop_check_proc(void *priv, void *cookie, int depth) 
			ep_tovisit = epi->ffd.file->private_data;

			if (ep_tovisit->gen == loop_check_gen)

				continue;

			if (!ep_push_nested(ep_tovisit)) {

			if (ep_tovisit == inserting_into || depth > EP_MAX_NESTS) {

				error = -1;

			} else {

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

						   depth + 1);

				nesting--;

			}

			if (error != 0)

				break;
@@ -1928,12 +1911,8 @@ static int ep_loop_check_proc(void *priv, void *cookie, int depth) 
 */

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

{

	int err;



	ep_push_nested(ep); // can't fail

	err = ep_loop_check_proc(file, ep, 0);

	nesting--;

	return err;

	inserting_into = ep;

	return ep_loop_check_proc(file, ep, 0);

}



static void clear_tfile_check_list(void)