[Xen-changelog] [xen-unstable] gnttab: for sanity's sake, don't access the active grant table

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1242773068 -3600
# Node ID 145e49b8574c8da3a72932a57c076227d38fee60
# Parent  d8d0f32090cb04ef6f81db8bc4ccdb9fa6113bf9
gnttab: for sanity's sake, don't access the active grant table
structure when we don't hold the lock.

Signed-off-by: Steven Smith <steven.smith@xxxxxxxxxx>
---
 xen/common/grant_table.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletion(-)

diff -r d8d0f32090cb -r 145e49b8574c xen/common/grant_table.c
--- a/xen/common/grant_table.c  Tue May 19 23:30:32 2009 +0100
+++ b/xen/common/grant_table.c  Tue May 19 23:44:28 2009 +0100
@@ -199,6 +199,7 @@ __gnttab_map_grant_ref(
     unsigned long  frame = 0, nr_gets = 0;
     int            rc = GNTST_okay;
     u32            old_pin;
+    u32            act_pin;
     unsigned int   cache_flags;
     struct active_grant_entry *act;
     struct grant_mapping *mt;
@@ -329,6 +330,7 @@ __gnttab_map_grant_ref(
             GNTPIN_hstr_inc : GNTPIN_hstw_inc;
 
     frame = act->frame;
+    act_pin = act->pin;
 
     cache_flags = (sha->flags & (GTF_PAT | GTF_PWT | GTF_PCD) );
 
@@ -391,7 +393,7 @@ __gnttab_map_grant_ref(
 
     if ( need_iommu(ld) &&
          !(old_pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) &&
-         (act->pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) )
+         (act_pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) )
     {
         if ( iommu_map_page(ld, mfn_to_gmfn(ld, frame), frame) )
         {

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