Index: linux-2.6.mod/fs/eventfd.c
===================================================================
--- linux-2.6.mod.orig/fs/eventfd.c	2009-06-20 16:25:45.000000000 -0700
+++ linux-2.6.mod/fs/eventfd.c	2009-06-21 09:36:46.000000000 -0700
@@ -17,8 +17,10 @@
 #include <linux/eventfd.h>
 #include <linux/syscalls.h>
 #include <linux/module.h>
+#include <linux/kref.h>
 
 struct eventfd_ctx {
+	struct kref kref;
 	wait_queue_head_t wqh;
 	/*
 	 * Every time that a write(2) is performed on an eventfd, the
@@ -59,9 +61,30 @@ int eventfd_signal(struct file *file, in
 }
 EXPORT_SYMBOL_GPL(eventfd_signal);
 
+static void eventfd_free(struct kref *kref)
+{
+	struct eventfd_ctx *ctx = container_of(kref, struct eventfd_ctx, kref);
+
+	kfree(ctx);
+}
+
+static struct eventfd_ctx *eventfd_get(struct eventfd_ctx *ctx)
+{
+	kref_get(&ctx->kref);
+	return ctx;
+}
+
+static void eventfd_put(struct eventfd_ctx *ctx)
+{
+	kref_put(&ctx->kref, eventfd_free);
+}
+
 static int eventfd_release(struct inode *inode, struct file *file)
 {
-	kfree(file->private_data);
+	struct eventfd_ctx *ctx = file->private_data;
+
+	wake_up_poll(&ctx->wqh, POLLHUP);
+	eventfd_put(ctx);
 	return 0;
 }
 
@@ -185,6 +208,14 @@ static const struct file_operations even
 	.write		= eventfd_write,
 };
 
+/**
+ * eventfd_fget - Acquire a reference of an eventfd file descriptor.
+ *
+ * @fd: [in] Eventfd file descriptor.
+ *
+ * Returns: A pointer to the eventfd file structure in case of success, or a
+ *          proper error pointer in case of failure.
+ */
 struct file *eventfd_fget(int fd)
 {
 	struct file *file;
@@ -217,6 +248,7 @@ SYSCALL_DEFINE2(eventfd2, unsigned int, 
 	if (!ctx)
 		return -ENOMEM;
 
+	kref_init(&ctx->kref);
 	init_waitqueue_head(&ctx->wqh);
 	ctx->count = count;
 	ctx->flags = flags;
@@ -237,3 +269,63 @@ SYSCALL_DEFINE1(eventfd, unsigned int, c
 	return sys_eventfd2(count, 0);
 }
 
+static void eventfd_pollcb_ptqueue(struct file *file, wait_queue_head_t *wqh,
+				   poll_table *pt)
+{
+	struct eventfd_pollcb *ecb;
+
+	ecb = container_of(pt, struct eventfd_pollcb, pt);
+
+	add_wait_queue(wqh, &ecb->wait);
+}
+
+/**
+ * eventfd_pollcb_register - Registers a wakeup callback with the eventfd
+ *                           file. The wakeup callback will be called from
+ *                           atomic context, and should handle the POLLHUP
+ *                           event accordingly in order to notice the last
+ *                           instance of the eventfd descriptor going away.
+ *
+ * @file: [in] Pointer to the eventfd file.
+ * @ecb: [out] Pointer to the eventfd callback structure.
+ * @cbf: [in] Pointer to the wakeup callback function.
+ * @events: [out] Pointer to the events that were ready at the time of the
+ *                callback registration.
+ *
+ * Returns: Zero in case of success, or a proper error code.
+ */
+int eventfd_pollcb_register(struct file *file, struct eventfd_pollcb *ecb,
+			    wait_queue_func_t cbf, unsigned int *events)
+{
+	struct eventfd_ctx *ctx;
+
+	ctx = file->private_data;
+	if (file->f_op != &eventfd_fops)
+		return -EINVAL;
+
+	init_waitqueue_func_entry(&ecb->wait, cbf);
+	init_poll_funcptr(&ecb->pt, eventfd_pollcb_ptqueue);
+	ecb->ctx = eventfd_get(ctx);
+
+	*events = file->f_op->poll(file, &ecb->pt);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(eventfd_pollcb_register);
+
+/**
+ * eventfd_pollcb_unregister - Unregisters a wakeup callback previously registered
+ *                             with eventfd_pollcb_register().
+ *
+ * @ecb: [in] Pointer to the eventfd callback structure previously registered with
+ *            eventfd_pollcb_register().
+ *
+ * Returns: Nothing.
+ */
+void eventfd_pollcb_unregister(struct eventfd_pollcb *ecb)
+{
+	remove_wait_queue(&ecb->ctx->wqh, &ecb->wait);
+	eventfd_put(ecb->ctx);
+}
+EXPORT_SYMBOL_GPL(eventfd_pollcb_unregister);
+
Index: linux-2.6.mod/include/linux/eventfd.h
===================================================================
--- linux-2.6.mod.orig/include/linux/eventfd.h	2009-06-20 16:25:45.000000000 -0700
+++ linux-2.6.mod/include/linux/eventfd.h	2009-06-21 09:37:12.000000000 -0700
@@ -8,6 +8,20 @@
 #ifndef _LINUX_EVENTFD_H
 #define _LINUX_EVENTFD_H
 
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/list.h>
+#include <linux/kref.h>
+
+struct eventfd_ctx;
+
+struct eventfd_pollcb {
+	poll_table pt;
+	struct eventfd_ctx *ctx;
+	wait_queue_t wait;
+};
+
 #ifdef CONFIG_EVENTFD
 
 /* For O_CLOEXEC and O_NONBLOCK */
@@ -29,12 +43,22 @@
 
 struct file *eventfd_fget(int fd);
 int eventfd_signal(struct file *file, int n);
+int eventfd_pollcb_register(struct file *file, struct eventfd_pollcb *ecb,
+			    wait_queue_func_t cbf, unsigned int *events);
+void eventfd_pollcb_unregister(struct eventfd_pollcb *ecb);
 
 #else /* CONFIG_EVENTFD */
 
 #define eventfd_fget(fd) ERR_PTR(-ENOSYS)
 static inline int eventfd_signal(struct file *file, int n)
 { return 0; }
+static inline int eventfd_pollcb_register(struct file *file,
+					  struct eventfd_pollcb *ecb,
+					  wait_queue_func_t cbf,
+					  unsigned int *events)
+{ return -ENOSYS; }
+static inline void eventfd_pollcb_unregister(struct eventfd_pollcb *ecb)
+{ }
 
 #endif /* CONFIG_EVENTFD */
 
