linux-kernel - [PATCH 6/6] xen/hvc: handle backend CLOSED without CLOSING

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Message-ID: <1348243464-15903-7-git-send-email-david.vrabel@citrix.com>
Date:	Fri, 21 Sep 2012 17:04:24 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	xen-devel@...ts.xensource.com
CC:	"David Vrabel" <david.vrabel@...rix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] xen/hvc: handle backend CLOSED without CLOSING

From: David Vrabel <david.vrabel@...rix.com>

Backend drivers shouldn't transistion to CLOSED unless the frontend is
CLOSED.  If a backend does transition to CLOSED too soon then the
frontend may not see the CLOSING state and will not properly shutdown.

So, treat an unexpected backend CLOSED state the same as CLOSING.

Signed-off-by: David Vrabel <david.vrabel@...rix.com>
---
 drivers/tty/hvc/hvc_xen.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 1e456dc..82901fb 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -476,7 +476,6 @@ static void xencons_backend_changed(struct xenbus_device *dev,
 	case XenbusStateInitialising:
 	case XenbusStateInitialised:
 	case XenbusStateUnknown:
-	case XenbusStateClosed:
 		break;
 
 	case XenbusStateInitWait:
@@ -486,6 +485,10 @@ static void xencons_backend_changed(struct xenbus_device *dev,
 		xenbus_switch_state(dev, XenbusStateConnected);
 		break;
 
+	case XenbusStateClosed:
+		if (dev->state == XenbusStateClosed)
+			break;
+		/* Missed the backend's CLOSING state -- fallthrough */
 	case XenbusStateClosing:
 		xenbus_frontend_closed(dev);
 		break;
-- 
1.7.2.5

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