Index: linux-2.6.mod/fs/eventfd.c
===================================================================
--- linux-2.6.mod.orig/fs/eventfd.c	2010-01-06 12:37:28.000000000 -0800
+++ linux-2.6.mod/fs/eventfd.c	2010-01-06 17:43:09.000000000 -0800
@@ -135,26 +135,56 @@ static unsigned int eventfd_poll(struct 
 	return events;
 }
 
-static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
-			    loff_t *ppos)
+/**
+ * eventfd_ctx_peek_value - Reads the eventfd counter.
+ * @ctx: [in] Pointer to eventfd context.
+ *
+ * NOTE: Must be called with the wait queue lock held.  Locking the
+ * eventfd_ctx interface is not actually exposed outside of the
+ * eventfd implementation, but when poll callback registers with the
+ * eventfd poll, such callbacks will be invoked with the wait queue
+ * lock held.  IOW this means that this function can only be called from
+ * inside a registered poll callback at the moment.
+ * The function returns the current counter value, without consuming it.
+ */
+__u64 eventfd_ctx_peek_value(struct eventfd_ctx *ctx)
+{
+	assert_spin_locked(&ctx->wqh.lock);
+
+	return ctx->count;
+}
+EXPORT_SYMBOL_GPL(eventfd_ctx_peek_value);
+
+/**
+ * eventfd_ctx_read - Reads the eventfd counter or wait if it is zero.
+ * @ctx: [in] Pointer to eventfd context.
+ * @no_wait: [in] Different from zero if the operation should not block.
+ * @cnt: [out] Pointer to the 64bit conter value.
+ *
+ * Returns zero if successful, or the following error codes:
+ *
+ * -EAGAIN      : The operation would have blocked but @no_wait was nonzero.
+ * -ERESTARTSYS : A signal interrupted the wait operation.
+ *
+ * If @no_wait is zero, the function might sleep until the eventfd internal
+ * counter becomes greater than zero.
+ */
+ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt)
 {
-	struct eventfd_ctx *ctx = file->private_data;
 	ssize_t res;
-	__u64 ucnt = 0;
 	DECLARE_WAITQUEUE(wait, current);
 
-	if (count < sizeof(ucnt))
-		return -EINVAL;
 	spin_lock_irq(&ctx->wqh.lock);
+	*cnt = 0;
 	res = -EAGAIN;
 	if (ctx->count > 0)
-		res = sizeof(ucnt);
-	else if (!(file->f_flags & O_NONBLOCK)) {
+		res = 0;
+	else if (!no_wait) {
 		__add_wait_queue(&ctx->wqh, &wait);
-		for (res = 0;;) {
+		for (;;) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (ctx->count > 0) {
-				res = sizeof(ucnt);
+				res = 0;
 				break;
 			}
 			if (signal_pending(current)) {
@@ -168,18 +198,32 @@ static ssize_t eventfd_read(struct file 
 		__remove_wait_queue(&ctx->wqh, &wait);
 		__set_current_state(TASK_RUNNING);
 	}
-	if (likely(res > 0)) {
-		ucnt = (ctx->flags & EFD_SEMAPHORE) ? 1 : ctx->count;
-		ctx->count -= ucnt;
+	if (likely(res == 0)) {
+		*cnt = (ctx->flags & EFD_SEMAPHORE) ? 1: ctx->count;
+		ctx->count -= *cnt;
 		if (waitqueue_active(&ctx->wqh))
 			wake_up_locked_poll(&ctx->wqh, POLLOUT);
 	}
 	spin_unlock_irq(&ctx->wqh.lock);
-	if (res > 0 && put_user(ucnt, (__u64 __user *) buf))
-		return -EFAULT;
 
 	return res;
 }
+EXPORT_SYMBOL_GPL(eventfd_ctx_read);
+
+static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
+			    loff_t *ppos)
+{
+	struct eventfd_ctx *ctx = file->private_data;
+	ssize_t res;
+	__u64 cnt;
+
+	if (count < sizeof(cnt))
+		return -EINVAL;
+	if ((res = eventfd_ctx_read(ctx, file->f_flags & O_NONBLOCK, &cnt)) < 0)
+		return res;
+
+	return put_user(cnt, (__u64 __user *) buf) ? -EFAULT: sizeof(cnt);
+}
 
 static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count,
 			     loff_t *ppos)
Index: linux-2.6.mod/include/linux/eventfd.h
===================================================================
--- linux-2.6.mod.orig/include/linux/eventfd.h	2010-01-06 12:37:28.000000000 -0800
+++ linux-2.6.mod/include/linux/eventfd.h	2010-01-06 14:54:36.000000000 -0800
@@ -34,6 +34,8 @@ struct file *eventfd_fget(int fd);
 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
 int eventfd_signal(struct eventfd_ctx *ctx, int n);
+ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
+__u64 eventfd_ctx_peek_value(struct eventfd_ctx *ctx);
 
 #else /* CONFIG_EVENTFD */
 
@@ -61,6 +63,17 @@ static inline void eventfd_ctx_put(struc
 
 }
 
+static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
+				       __u64 *cnt)
+{
+	return -ENOSYS;
+}
+
+static inline __u64 eventfd_ctx_peek_value(struct eventfd_ctx *ctx)
+{
+	return 0;
+}
+
 #endif
 
 #endif /* _LINUX_EVENTFD_H */
