From: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Date: Thu, 26 Jan 2012 13:21:27 +0000 (+0000)
Subject: x86/mm: Fix p2m teardown locking
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=ad6c917d7da2cc1dbcb6c8aa19ee0f9866d76f4e;p=xen.git

x86/mm: Fix p2m teardown locking

Holding the p2m lock during a p2m teardown, while unsharing entries pointing to
shared frames, causes a locking inversion and deadlock panic.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
---

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index eb43683a03..edcd09f24f 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -343,8 +343,6 @@ void p2m_teardown(struct p2m_domain *p2m)
     if (p2m == NULL)
         return;
 
-    p2m_lock(p2m);
-
 #ifdef __x86_64__
     for ( gfn=0; gfn < p2m->max_mapped_pfn; gfn++ )
     {
@@ -358,6 +356,8 @@ void p2m_teardown(struct p2m_domain *p2m)
     }
 #endif
 
+    p2m_lock(p2m);
+
     p2m->phys_table = pagetable_null();
 
     while ( (pg = page_list_remove_head(&p2m->pages)) )