Content-Transfer-Encoding: 7bit
Subject: [PATCH] implement O_NONBLOCK for /proc/xen/xenbus
X-Mercurial-Node: 29260da8baac276184bd4266863c0e69d62b9634
Message-Id: <29260da8baac276184bd.1277396873@xxxxxxxxxxxxxxxxxxxxxxx>
User-Agent: Mercurial-patchbomb/1.5.3
Date: Thu, 24 Jun 2010 18:27:53 +0200
From: pbonzini@xxxxxxxxxx
To: pbonzini@xxxxxxxxxx

# HG changeset patch
# User Paolo Bonzini <pbonzini@xxxxxxxxxx>
# Date 1277396822 -7200
# Node ID 29260da8baac276184bd4266863c0e69d62b9634
# Parent  f66d155ce457dab7a191bc199e878c07c2d2aead
implement O_NONBLOCK for /proc/xen/xenbus

This patch implements O_NONBLOCK for /proc/xen/xenbus.  It is a simple
matter of returning -EAGAIN instead of waiting on a queue.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>

diff --git a/drivers/xen/xenbus/xenbus_dev.c b/drivers/xen/xenbus/xenbus_dev.c
--- a/drivers/xen/xenbus/xenbus_dev.c
+++ b/drivers/xen/xenbus/xenbus_dev.c
@@ -104,6 +104,9 @@
 	mutex_lock(&u->reply_mutex);
 	while (list_empty(&u->read_buffers)) {
 		mutex_unlock(&u->reply_mutex);
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
 		ret = wait_event_interruptible(u->read_waitq,
 					       !list_empty(&u->read_buffers));
 		if (ret)