Merge branch 'work.epoll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs (1a825a6a) · Commits · 戴 / test

Pull epoll updates from Al Viro: "Deal with epoll loop check/removal races sanely (among other things). The solution merged last cycle (pinning a bunch of struct file instances) had been forced by the wrong data structures; untangling that takes a bunch of preparations, but it's worth doing - control flow in there is ridiculously overcomplicated. Memory footprint has also gone down, while we are at it. This is not all I want to do in the area, but since I didn't get around to posting the followups they'll have to wait for the next cycle" * 'work.epoll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (27 commits) epoll: take epitem list out of struct file epoll: massage the check list insertion lift rcu_read_lock() into reverse_path_check() convert ->f_ep_links/->fllink to hlist ep_insert(): move creation of wakeup source past the fl_ep_links insertion fold ep_read_events_proc() into the only caller take the common part of ep_eventpoll_poll() and ep_item_poll() into helper ep_insert(): we only need tep->mtx around the insertion itself ep_insert(): don't open-code ep_remove() on failure exits lift locking/unlocking ep->mtx out of ep_{start,done}_scan() ep_send_events_proc(): fold into the caller lift the calls of ep_send_events_proc() into the callers lift the calls of ep_read_events_proc() into the callers ep_scan_ready_list(): prepare to splitup ep_loop_check_proc(): saner calling conventions get rid of ep_push_nested() ep_loop_check_proc(): lift pushing the cookie into callers clean reverse_path_check_proc() a bit reverse_path_check_proc(): don't bother with cookies reverse_path_check_proc(): sane arguments ...

fs/eventpoll.c

+302 −415

File changed.

Preview size limit exceeded, changes collapsed.

fs/file_table.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -113,7 +113,6 @@ static struct file __alloc_file(int flags, const struct cred cred)
		rwlock_init(&f->f_owner.lock);
		spin_lock_init(&f->f_lock);
		mutex_init(&f->f_pos_lock);
		eventpoll_init_file(f);
		f->f_flags = flags;
		f->f_mode = OPEN_FMODE(flags);
		/* f->f_version: 0 */

include/linux/eventpoll.h

+1 −10

Original line number	Diff line number	Diff line
		@@ -22,14 +22,6 @@ struct file;
		struct file get_epoll_tfile_raw_ptr(struct file file, int tfd, unsigned long toff);
		#endif

		/* Used to initialize the epoll bits inside the "struct file" */
		static inline void eventpoll_init_file(struct file *file)
		{
		INIT_LIST_HEAD(&file->f_ep_links);
		INIT_LIST_HEAD(&file->f_tfile_llink);
		}


		/* Used to release the epoll bits inside the "struct file" */
		void eventpoll_release_file(struct file *file);

		@@ -50,7 +42,7 @@ static inline void eventpoll_release(struct file *file)
		* because the file in on the way to be removed and nobody ( but
		* eventpoll ) has still a reference to this file.
		*/
		if (likely(list_empty(&file->f_ep_links)))
		if (likely(!file->f_ep))
		return;

		/*
		@@ -72,7 +64,6 @@ static inline int ep_op_has_event(int op)

		#else

		static inline void eventpoll_init_file(struct file *file) {}
		static inline void eventpoll_release(struct file *file) {}

		#endif

include/linux/fs.h

+2 −3

Original line number	Diff line number	Diff line
		@@ -923,7 +923,7 @@ struct file {
		const struct file_operations *f_op;

		/*
		* Protects f_ep_links, f_flags.
		* Protects f_ep, f_flags.
		* Must not be taken from IRQ context.
		*/
		spinlock_t f_lock;
		@@ -946,8 +946,7 @@ struct file {

		#ifdef CONFIG_EPOLL
		/* Used by fs/eventpoll.c to link all the hooks to this file */
		struct list_head f_ep_links;
		struct list_head f_tfile_llink;
		struct hlist_head *f_ep;
		#endif /* #ifdef CONFIG_EPOLL */
		struct address_space *f_mapping;
		errseq_t f_wb_err;

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