1 files changed, 53 insertions, 88 deletions

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 3627dd7d25db..3219e0d596fe 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -33,10 +33,10 @@ struct eventfd_ctx {
 	/*
 	 * Every time that a write(2) is performed on an eventfd, the
 	 * value of the __u64 being written is added to "count" and a
-	 * wakeup is performed on "wqh". A read(2) will return the "count"
-	 * value to userspace, and will reset "count" to zero. The kernel
-	 * side eventfd_signal() also, adds to the "count" counter and
-	 * issue a wakeup.
+	 * wakeup is performed on "wqh". If EFD_SEMAPHORE flag was not
+	 * specified, a read(2) will return the "count" value to userspace,
+	 * and will reset "count" to zero. The kernel side eventfd_signal()
+	 * also, adds to the "count" counter and issue a wakeup.
 	 */
 	__u64 count;
 	unsigned int flags;
@@ -44,20 +44,16 @@ struct eventfd_ctx {
 };
 
 /**
- * eventfd_signal - Adds @n to the eventfd counter.
+ * eventfd_signal_mask - Increment the event counter
  * @ctx: [in] Pointer to the eventfd context.
- * @n: [in] Value of the counter to be added to the eventfd internal counter.
- *          The value cannot be negative.
+ * @mask: [in] poll mask
  *
  * This function is supposed to be called by the kernel in paths that do not
  * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
  * value, and we signal this as overflow condition by returning a EPOLLERR
  * to poll(2).
- *
- * Returns the amount by which the counter was incremented.  This will be less
- * than @n if the counter has overflowed.
  */
-__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
+void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
 {
 	unsigned long flags;
 
@@ -69,27 +65,24 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
 	 * it returns false, the eventfd_signal() call should be deferred to a
 	 * safe context.
 	 */
-	if (WARN_ON_ONCE(current->in_eventfd_signal))
-		return 0;
+	if (WARN_ON_ONCE(current->in_eventfd))
+		return;
 
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
-	current->in_eventfd_signal = 1;
-	if (ULLONG_MAX - ctx->count < n)
-		n = ULLONG_MAX - ctx->count;
-	ctx->count += n;
+	current->in_eventfd = 1;
+	if (ctx->count < ULLONG_MAX)
+		ctx->count++;
 	if (waitqueue_active(&ctx->wqh))
-		wake_up_locked_poll(&ctx->wqh, EPOLLIN);
-	current->in_eventfd_signal = 0;
+		wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
+	current->in_eventfd = 0;
 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
-
-	return n;
 }
-EXPORT_SYMBOL_GPL(eventfd_signal);
+EXPORT_SYMBOL_GPL(eventfd_signal_mask);
 
 static void eventfd_free_ctx(struct eventfd_ctx *ctx)
 {
 	if (ctx->id >= 0)
-		ida_simple_remove(&eventfd_ida, ctx->id);
+		ida_free(&eventfd_ida, ctx->id);
 	kfree(ctx);
 }
 
@@ -184,7 +177,7 @@ void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
 {
 	lockdep_assert_held(&ctx->wqh.lock);
 
-	*cnt = (ctx->flags & EFD_SEMAPHORE) ? 1 : ctx->count;
+	*cnt = ((ctx->flags & EFD_SEMAPHORE) && ctx->count) ? 1 : ctx->count;
 	ctx->count -= *cnt;
 }
 EXPORT_SYMBOL_GPL(eventfd_ctx_do_read);
@@ -223,7 +216,6 @@ static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *to)
 	struct file *file = iocb->ki_filp;
 	struct eventfd_ctx *ctx = file->private_data;
 	__u64 ucnt = 0;
-	DECLARE_WAITQUEUE(wait, current);
 
 	if (iov_iter_count(to) < sizeof(ucnt))
 		return -EINVAL;
@@ -234,27 +226,17 @@ static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *to)
 			spin_unlock_irq(&ctx->wqh.lock);
 			return -EAGAIN;
 		}
-		__add_wait_queue(&ctx->wqh, &wait);
-		for (;;) {
-			set_current_state(TASK_INTERRUPTIBLE);
-			if (ctx->count)
-				break;
-			if (signal_pending(current)) {
-				__remove_wait_queue(&ctx->wqh, &wait);
-				__set_current_state(TASK_RUNNING);
-				spin_unlock_irq(&ctx->wqh.lock);
-				return -ERESTARTSYS;
-			}
+
+		if (wait_event_interruptible_locked_irq(ctx->wqh, ctx->count)) {
 			spin_unlock_irq(&ctx->wqh.lock);
-			schedule();
-			spin_lock_irq(&ctx->wqh.lock);
+			return -ERESTARTSYS;
 		}
-		__remove_wait_queue(&ctx->wqh, &wait);
-		__set_current_state(TASK_RUNNING);
 	}
 	eventfd_ctx_do_read(ctx, &ucnt);
+	current->in_eventfd = 1;
 	if (waitqueue_active(&ctx->wqh))
 		wake_up_locked_poll(&ctx->wqh, EPOLLOUT);
+	current->in_eventfd = 0;
 	spin_unlock_irq(&ctx->wqh.lock);
 	if (unlikely(copy_to_iter(&ucnt, sizeof(ucnt), to) != sizeof(ucnt)))
 		return -EFAULT;
@@ -268,9 +250,8 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
 	struct eventfd_ctx *ctx = file->private_data;
 	ssize_t res;
 	__u64 ucnt;
-	DECLARE_WAITQUEUE(wait, current);
 
-	if (count < sizeof(ucnt))
+	if (count != sizeof(ucnt))
 		return -EINVAL;
 	if (copy_from_user(&ucnt, buf, sizeof(ucnt)))
 		return -EFAULT;
@@ -281,28 +262,17 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
 	if (ULLONG_MAX - ctx->count > ucnt)
 		res = sizeof(ucnt);
 	else if (!(file->f_flags & O_NONBLOCK)) {
-		__add_wait_queue(&ctx->wqh, &wait);
-		for (res = 0;;) {
-			set_current_state(TASK_INTERRUPTIBLE);
-			if (ULLONG_MAX - ctx->count > ucnt) {
-				res = sizeof(ucnt);
-				break;
-			}
-			if (signal_pending(current)) {
-				res = -ERESTARTSYS;
-				break;
-			}
-			spin_unlock_irq(&ctx->wqh.lock);
-			schedule();
-			spin_lock_irq(&ctx->wqh.lock);
-		}
-		__remove_wait_queue(&ctx->wqh, &wait);
-		__set_current_state(TASK_RUNNING);
+		res = wait_event_interruptible_locked_irq(ctx->wqh,
+				ULLONG_MAX - ctx->count > ucnt);
+		if (!res)
+			res = sizeof(ucnt);
 	}
 	if (likely(res > 0)) {
 		ctx->count += ucnt;
+		current->in_eventfd = 1;
 		if (waitqueue_active(&ctx->wqh))
 			wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+		current->in_eventfd = 0;
 	}
 	spin_unlock_irq(&ctx->wqh.lock);
 
@@ -313,12 +283,19 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
 static void eventfd_show_fdinfo(struct seq_file *m, struct file *f)
 {
 	struct eventfd_ctx *ctx = f->private_data;
+	__u64 cnt;
 
 	spin_lock_irq(&ctx->wqh.lock);
-	seq_printf(m, "eventfd-count: %16llx\n",
-		   (unsigned long long)ctx->count);
+	cnt = ctx->count;
 	spin_unlock_irq(&ctx->wqh.lock);
-	seq_printf(m, "eventfd-id: %d\n", ctx->id);
+
+	seq_printf(m,
+		   "eventfd-count: %16llx\n"
+		   "eventfd-id: %d\n"
+		   "eventfd-semaphore: %d\n",
+		   cnt,
+		   ctx->id,
+		   !!(ctx->flags & EFD_SEMAPHORE));
 }
 #endif
 
@@ -370,13 +347,10 @@ EXPORT_SYMBOL_GPL(eventfd_fget);
  */
 struct eventfd_ctx *eventfd_ctx_fdget(int fd)
 {
-	struct eventfd_ctx *ctx;
-	struct fd f = fdget(fd);
-	if (!f.file)
+	CLASS(fd, f)(fd);
+	if (fd_empty(f))
 		return ERR_PTR(-EBADF);
-	ctx = eventfd_ctx_fileget(f.file);
-	fdput(f);
-	return ctx;
+	return eventfd_ctx_fileget(fd_file(f));
 }
 EXPORT_SYMBOL_GPL(eventfd_ctx_fdget);
 
@@ -404,13 +378,12 @@ EXPORT_SYMBOL_GPL(eventfd_ctx_fileget);
 
 static int do_eventfd(unsigned int count, int flags)
 {
-	struct eventfd_ctx *ctx;
-	struct file *file;
-	int fd;
+	struct eventfd_ctx *ctx __free(kfree) = NULL;
 
 	/* Check the EFD_* constants for consistency.  */
 	BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
 	BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK);
+	BUILD_BUG_ON(EFD_SEMAPHORE != (1 << 0));
 
 	if (flags & ~EFD_FLAGS_SET)
 		return -EINVAL;
@@ -423,27 +396,19 @@ static int do_eventfd(unsigned int count, int flags)
 	init_waitqueue_head(&ctx->wqh);
 	ctx->count = count;
 	ctx->flags = flags;
-	ctx->id = ida_simple_get(&eventfd_ida, 0, 0, GFP_KERNEL);
 
 	flags &= EFD_SHARED_FCNTL_FLAGS;
 	flags |= O_RDWR;
-	fd = get_unused_fd_flags(flags);
-	if (fd < 0)
-		goto err;
-
-	file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx, flags);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		fd = PTR_ERR(file);
-		goto err;
-	}
 
-	file->f_mode |= FMODE_NOWAIT;
-	fd_install(fd, file);
-	return fd;
-err:
-	eventfd_free_ctx(ctx);
-	return fd;
+	FD_PREPARE(fdf, flags,
+		   anon_inode_getfile_fmode("[eventfd]", &eventfd_fops, ctx,
+					    flags, FMODE_NOWAIT));
+	if (fdf.err)
+		return fdf.err;
+
+	ctx->id = ida_alloc(&eventfd_ida, GFP_KERNEL);
+	retain_and_null_ptr(ctx);
+	return fd_publish(fdf);
 }
 
 SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)