[Xen-changelog] Apply proper locking in xenlinux mtrr interface functions.

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

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID e0d32d7cb5da9f898562dd4eea3fd2661e2812c6
# Parent  c176d2e45117afdba901affcf0d73b2e2acff9b7
Apply proper locking in xenlinux mtrr interface functions.

From: Jan Beulich
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r c176d2e45117 -r e0d32d7cb5da 
linux-2.6-xen-sparse/arch/i386/kernel/cpu/mtrr/main-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/kernel/cpu/mtrr/main-xen.c Thu Mar  9 
14:57:32 2006
+++ b/linux-2.6-xen-sparse/arch/i386/kernel/cpu/mtrr/main-xen.c Thu Mar  9 
14:59:53 2006
@@ -7,6 +7,8 @@
 
 #include <asm/mtrr.h>
 #include "mtrr.h"
+
+static DECLARE_MUTEX(mtrr_sem);
 
 void generic_get_mtrr(unsigned int reg, unsigned long *base,
                      unsigned int *size, mtrr_type * type)
@@ -63,18 +65,23 @@
        int error;
        dom0_op_t op;
 
+       down(&mtrr_sem);
+
        op.cmd = DOM0_ADD_MEMTYPE;
        op.u.add_memtype.mfn     = base;
        op.u.add_memtype.nr_mfns = size;
        op.u.add_memtype.type    = type;
        error = HYPERVISOR_dom0_op(&op);
        if (error) {
+               up(&mtrr_sem);
                BUG_ON(error > 0);
                return error;
        }
 
        if (increment)
                ++usage_table[op.u.add_memtype.reg];
+
+       up(&mtrr_sem);
 
        return op.u.add_memtype.reg;
 }
@@ -104,17 +111,18 @@
 
 int mtrr_del_page(int reg, unsigned long base, unsigned long size)
 {
-       int i, max;
+       unsigned i;
        mtrr_type ltype;
        unsigned long lbase;
        unsigned int lsize;
        int error = -EINVAL;
        dom0_op_t op;
 
-       max = num_var_ranges;
+       down(&mtrr_sem);
+
        if (reg < 0) {
                /*  Search for existing MTRR  */
-               for (i = 0; i < max; ++i) {
+               for (i = 0; i < num_var_ranges; ++i) {
                        mtrr_if->get(i, &lbase, &lsize, &ltype);
                        if (lbase == base && lsize == size) {
                                reg = i;
@@ -143,6 +151,7 @@
        }
        error = reg;
  out:
+       up(&mtrr_sem);
        return error;
 }
 

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