[Xen-changelog] [xen-3.1-testing] pvfb: PVFB frontend can send bogus screen updates

["Xen patchbot-3.1-testing" <patchbot-3.1-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1196963052 0
# Node ID 0462bf70c6b9382fba4953a155a842b73202cfab
# Parent  1177efd2500e84b5a8cee0d94541a8decffd1d2d
pvfb: PVFB frontend can send bogus screen updates

The PVFB frontend can get confused and send a screen update to the
backend when the screen is actually clean.  Such an update asks for
the impossible rectangle (x1, x2, y1, y2) = (INT_MAX, 0, INT_MAX, 0).
Fix by setting the dirty flag in the obvious place: when the dirty
rectangle is grown.

Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
linux-2.6.18-xen changeset:   311:ca05cf1a9bdc2c7604b95fd085fa5abe067c969a
linux-2.6.18-xen date:        Fri Nov 16 16:55:46 2007 +0000
---
 linux-2.6-xen-sparse/drivers/xen/fbfront/xenfb.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -r 1177efd2500e -r 0462bf70c6b9 
linux-2.6-xen-sparse/drivers/xen/fbfront/xenfb.c
--- a/linux-2.6-xen-sparse/drivers/xen/fbfront/xenfb.c  Thu Dec 06 17:41:12 
2007 +0000
+++ b/linux-2.6-xen-sparse/drivers/xen/fbfront/xenfb.c  Thu Dec 06 17:44:12 
2007 +0000
@@ -201,6 +201,11 @@ static void xenfb_update_screen(struct x
 
        mutex_unlock(&info->mm_lock);
 
+       if (x2 < x1 || y2 < y1) {
+               printk("xenfb_update_screen bogus rect %d %d %d %d\n",
+                      x1, x2, y1, y2);
+               WARN_ON(1);
+       }
        xenfb_do_update(info, x1, y1, x2 - x1, y2 - y1);
 }
 
@@ -252,7 +257,6 @@ static void xenfb_timer(unsigned long da
 static void xenfb_timer(unsigned long data)
 {
        struct xenfb_info *info = (struct xenfb_info *)data;
-       info->dirty = 1;
        wake_up(&info->wq);
 }
 
@@ -272,6 +276,7 @@ static void __xenfb_refresh(struct xenfb
                info->x1 = x1;
        if (info->x2 < x2)
                info->x2 = x2;
+       info->dirty = 1;
 
        if (timer_pending(&info->refresh))
                return;

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