diff --git a/fs/eventfd.c b/fs/eventfd.c
index 35470d9..8f821b1 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -2,6 +2,7 @@
  *  fs/eventfd.c
  *
  *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
+ *  Copyright (C) 2013  Martin Sustrik <sustrik@250bpm.com>
  *
  */
 
@@ -22,18 +23,31 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 
+#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
+#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE | EFD_MASK)
+#define EFD_MASK_VALID_EVENTS (POLLIN | POLLPRI | POLLOUT | POLLERR | POLLHUP)
+
 struct eventfd_ctx {
 	struct kref kref;
 	wait_queue_head_t wqh;
-	/*
-	 * 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.
-	 */
-	__u64 count;
+	union {
+		/*
+		 * 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.
+		 */
+		__u64 count;
+
+		/*
+		 * When using eventfd in EFD_MASK mode this stracture stores the
+		 * current events to be signaled on the eventfd (events member)
+		 * along with opaque user-defined data (data member).
+		 */
+		struct efd_mask mask;
+	};
 	unsigned int flags;
 };
 
@@ -55,6 +69,9 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
 {
 	unsigned long flags;
 
+	/* This function should never be used with eventfd in the mask mode. */
+	BUG_ON(ctx->flags & EFD_MASK);
+
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
 	if (ULLONG_MAX - ctx->count < n)
 		n = ULLONG_MAX - ctx->count;
@@ -123,12 +140,16 @@ static unsigned int eventfd_poll(struct file *file, poll_table *wait)
 	poll_wait(file, &ctx->wqh, wait);
 
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
-	if (ctx->count > 0)
-		events |= POLLIN;
-	if (ctx->count == ULLONG_MAX)
-		events |= POLLERR;
-	if (ULLONG_MAX - 1 > ctx->count)
-		events |= POLLOUT;
+	if (ctx->flags & EFD_MASK) {
+		events = ctx->mask.events;
+	} else {
+		if (ctx->count > 0)
+			events |= POLLIN;
+		if (ctx->count == ULLONG_MAX)
+			events |= POLLERR;
+		if (ULLONG_MAX - 1 > ctx->count)
+			events |= POLLOUT;
+	}
 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
 
 	return events;
@@ -158,6 +179,9 @@ int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_t *wait,
 {
 	unsigned long flags;
 
+	/* This function should never be used with eventfd in the mask mode. */
+	BUG_ON(ctx->flags & EFD_MASK);
+
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
 	eventfd_ctx_do_read(ctx, cnt);
 	__remove_wait_queue(&ctx->wqh, wait);
@@ -188,6 +212,9 @@ ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt)
 	ssize_t res;
 	DECLARE_WAITQUEUE(wait, current);
 
+	/* This function should never be used with eventfd in the mask mode. */
+	BUG_ON(ctx->flags & EFD_MASK);
+
 	spin_lock_irq(&ctx->wqh.lock);
 	*cnt = 0;
 	res = -EAGAIN;
@@ -227,63 +254,92 @@ 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;
-	res = eventfd_ctx_read(ctx, file->f_flags & O_NONBLOCK, &cnt);
-	if (res < 0)
-		return res;
-
-	return put_user(cnt, (__u64 __user *) buf) ? -EFAULT : sizeof(cnt);
+	if (ctx->flags & EFD_MASK) {
+		struct efd_mask mask;
+		if (count < sizeof(mask))
+			return -EINVAL;
+		spin_lock_irq(&ctx->wqh.lock);
+		mask = ctx->mask;
+		spin_unlock_irq(&ctx->wqh.lock);
+		if (copy_to_user(buf, &mask, sizeof(mask)))
+			return -EFAULT;
+		return sizeof(mask);
+	} else {
+		ssize_t res;
+		__u64 cnt;
+		if (count < sizeof(cnt))
+			return -EINVAL;
+		res = eventfd_ctx_read(ctx, file->f_flags & O_NONBLOCK, &cnt);
+		if (res < 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)
 {
 	struct eventfd_ctx *ctx = file->private_data;
-	ssize_t res;
-	__u64 ucnt;
-	DECLARE_WAITQUEUE(wait, current);
 
-	if (count < sizeof(ucnt))
-		return -EINVAL;
-	if (copy_from_user(&ucnt, buf, sizeof(ucnt)))
-		return -EFAULT;
-	if (ucnt == ULLONG_MAX)
-		return -EINVAL;
-	spin_lock_irq(&ctx->wqh.lock);
-	res = -EAGAIN;
-	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;
+	if (ctx->flags & EFD_MASK) {
+		struct efd_mask mask;
+		if (count < sizeof(mask))
+			return -EINVAL;
+		if (copy_from_user(&mask, buf, sizeof(mask)))
+			return -EFAULT;
+		if (mask.events & ~EFD_MASK_VALID_EVENTS)
+			return -EINVAL;
+		spin_lock_irq(&ctx->wqh.lock);
+		memcpy(&ctx->mask, &mask, sizeof(ctx->mask));
+		if (waitqueue_active(&ctx->wqh))
+			wake_up_locked_poll(&ctx->wqh,
+				(unsigned long)ctx->mask.events);
+		spin_unlock_irq(&ctx->wqh.lock);
+		return sizeof(ctx->mask);
+	} else {
+		ssize_t res;
+		__u64 ucnt;
+		DECLARE_WAITQUEUE(wait, current);
+		if (count < sizeof(ucnt))
+			return -EINVAL;
+		if (copy_from_user(&ucnt, buf, sizeof(ucnt)))
+			return -EFAULT;
+		if (ucnt == ULLONG_MAX)
+			return -EINVAL;
+		spin_lock_irq(&ctx->wqh.lock);
+		res = -EAGAIN;
+		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);
 			}
-			spin_unlock_irq(&ctx->wqh.lock);
-			schedule();
-			spin_lock_irq(&ctx->wqh.lock);
+			__remove_wait_queue(&ctx->wqh, &wait);
+			__set_current_state(TASK_RUNNING);
 		}
-		__remove_wait_queue(&ctx->wqh, &wait);
-		__set_current_state(TASK_RUNNING);
-	}
-	if (likely(res > 0)) {
-		ctx->count += ucnt;
-		if (waitqueue_active(&ctx->wqh))
-			wake_up_locked_poll(&ctx->wqh, POLLIN);
-	}
-	spin_unlock_irq(&ctx->wqh.lock);
+		if (likely(res > 0)) {
+			ctx->count += ucnt;
+			if (waitqueue_active(&ctx->wqh))
+				wake_up_locked_poll(&ctx->wqh, POLLIN);
+		}
+		spin_unlock_irq(&ctx->wqh.lock);
 
-	return res;
+		return res;
+	}
 }
 
 #ifdef CONFIG_PROC_FS
@@ -293,8 +349,13 @@ static int eventfd_show_fdinfo(struct seq_file *m, struct file *f)
 	int ret;
 
 	spin_lock_irq(&ctx->wqh.lock);
-	ret = seq_printf(m, "eventfd-count: %16llx\n",
-			 (unsigned long long)ctx->count);
+	if (ctx->flags & EFD_MASK) {
+		ret = seq_printf(m, "eventfd-mask: %x\n",
+				 (unsigned)ctx->mask.events);
+	} else {
+		ret = seq_printf(m, "eventfd-count: %16llx\n",
+				 (unsigned long long)ctx->count);
+	}
 	spin_unlock_irq(&ctx->wqh.lock);
 
 	return ret;
@@ -412,7 +473,12 @@ struct file *eventfd_file_create(unsigned int count, int flags)
 
 	kref_init(&ctx->kref);
 	init_waitqueue_head(&ctx->wqh);
-	ctx->count = count;
+	if (flags & EFD_MASK) {
+		ctx->mask.events = 0;
+		ctx->mask.data = 0;
+	} else {
+		ctx->count = count;
+	}
 	ctx->flags = flags;
 
 	file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx,
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index 3c3ef19..218aba6 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -8,24 +8,11 @@
 #ifndef _LINUX_EVENTFD_H
 #define _LINUX_EVENTFD_H
 
-#include <linux/fcntl.h>
+#include <uapi/linux/eventfd.h>
+
 #include <linux/file.h>
 #include <linux/wait.h>
 
-/*
- * CAREFUL: Check include/asm-generic/fcntl.h when defining
- * new flags, since they might collide with O_* ones. We want
- * to re-use O_* flags that couldn't possibly have a meaning
- * from eventfd, in order to leave a free define-space for
- * shared O_* flags.
- */
-#define EFD_SEMAPHORE (1 << 0)
-#define EFD_CLOEXEC O_CLOEXEC
-#define EFD_NONBLOCK O_NONBLOCK
-
-#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
-#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
-
 #ifdef CONFIG_EVENTFD
 
 struct file *eventfd_file_create(unsigned int count, int flags);
diff --git a/include/uapi/linux/eventfd.h b/include/uapi/linux/eventfd.h
new file mode 100644
index 0000000..03057a5
--- /dev/null
+++ b/include/uapi/linux/eventfd.h
@@ -0,0 +1,40 @@
+/*
+ *  Copyright (C) 2013 Martin Sustrik <sustrik@250bpm.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#ifndef _UAPI_LINUX_EVENTFD_H
+#define _UAPI_LINUX_EVENTFD_H
+
+/* For O_CLOEXEC */
+#include <linux/fcntl.h>
+#include <linux/types.h>
+
+/*
+ * CAREFUL: Check include/asm-generic/fcntl.h when defining
+ * new flags, since they might collide with O_* ones. We want
+ * to re-use O_* flags that couldn't possibly have a meaning
+ * from eventfd, in order to leave a free define-space for
+ * shared O_* flags.
+ */
+
+/* Provide semaphore-like semantics for reads from the eventfd. */
+#define EFD_SEMAPHORE (1 << 0)
+/* Provide event mask semantics for the eventfd. */
+#define EFD_MASK (1 << 1)
+/*  Set the close-on-exec (FD_CLOEXEC) flag on the eventfd. */
+#define EFD_CLOEXEC O_CLOEXEC
+/*  Create the eventfd in non-blocking mode. */
+#define EFD_NONBLOCK O_NONBLOCK
+
+/* Structure to read/write to eventfd in EFD_MASK mode. */
+struct efd_mask {
+	__u32 events;
+	__u64 data;
+} __packed;
+
+#endif /* _UAPI_LINUX_EVENTFD_H */
