epoll: replace ->visited/visited_list with generation count (18306c40) · Commits · 戴 / test

fs/eventpoll.c

+8 −19

Original line number	Diff line number	Diff line
		@@ -218,8 +218,7 @@ struct eventpoll {
		struct file *file;

		/* used to optimize loop detection check */
		struct list_head visited_list_link;
		int visited;
		u64 gen;

		#ifdef CONFIG_NET_RX_BUSY_POLL
		/* used to track busy poll napi_id */
		@@ -274,6 +273,8 @@ static long max_user_watches __read_mostly;
		*/
		static DEFINE_MUTEX(epmutex);

		static u64 loop_check_gen = 0;

		/* Used to check for epoll file descriptor inclusion loops */
		static struct nested_calls poll_loop_ncalls;

		@@ -283,9 +284,6 @@ static struct kmem_cache *epi_cache __read_mostly;
		/* Slab cache used to allocate "struct eppoll_entry" */
		static struct kmem_cache *pwq_cache __read_mostly;

		/* Visited nodes during ep_loop_check(), so we can unset them when we finish */
		static LIST_HEAD(visited_list);

		/*
		* List of files with newly added links, where we may need to limit the number
		* of emanating paths. Protected by the epmutex.
		@@ -1971,13 +1969,12 @@ static int ep_loop_check_proc(void priv, void cookie, int call_nests)
		struct epitem *epi;

		mutex_lock_nested(&ep->mtx, call_nests + 1);
		ep->visited = 1;
		list_add(&ep->visited_list_link, &visited_list);
		ep->gen = loop_check_gen;
		for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
		epi = rb_entry(rbp, struct epitem, rbn);
		if (unlikely(is_file_epoll(epi->ffd.file))) {
		ep_tovisit = epi->ffd.file->private_data;
		if (ep_tovisit->visited)
		if (ep_tovisit->gen == loop_check_gen)
		continue;
		error = ep_call_nested(&poll_loop_ncalls,
		ep_loop_check_proc, epi->ffd.file,
		@@ -2018,18 +2015,8 @@ static int ep_loop_check_proc(void priv, void cookie, int call_nests)
		*/
		static int ep_loop_check(struct eventpoll ep, struct file file)
		{
		int ret;
		struct eventpoll ep_cur, ep_next;

		ret = ep_call_nested(&poll_loop_ncalls,
		return ep_call_nested(&poll_loop_ncalls,
		ep_loop_check_proc, file, ep, current);
		/* clear visited list */
		list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
		visited_list_link) {
		ep_cur->visited = 0;
		list_del(&ep_cur->visited_list_link);
		}
		return ret;
		}

		static void clear_tfile_check_list(void)
		@@ -2199,6 +2186,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
		error = epoll_mutex_lock(&epmutex, 0, nonblock);
		if (error)
		goto error_tgt_fput;
		loop_check_gen++;
		full_check = 1;
		if (is_file_epoll(tf.file)) {
		error = -ELOOP;
		@@ -2262,6 +2250,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
		error_tgt_fput:
		if (full_check) {
		clear_tfile_check_list();
		loop_check_gen++;
		mutex_unlock(&epmutex);
		}

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