[src/cherry-xenmp]: src/sys/arch/xen/xen Use a mutex to protect updates to gn...

[mhitch <mhitch%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fb191682ccda
branches:  cherry-xenmp
changeset: 765637:fb191682ccda
user:      mhitch <mhitch%NetBSD.org@localhost>
date:      Sun Sep 04 01:15:13 2011 +0000

description:
Use a mutex to protect updates to gnt_entries.  Fixes a KASSERT panic
with an MP kernel.

diffstat:

 sys/arch/xen/xen/xengnt.c |  18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diffs (84 lines):

diff -r d4527eb7c4a3 -r fb191682ccda sys/arch/xen/xen/xengnt.c
--- a/sys/arch/xen/xen/xengnt.c Thu Sep 01 08:04:46 2011 +0000
+++ b/sys/arch/xen/xen/xengnt.c Sun Sep 04 01:15:13 2011 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: xengnt.c,v 1.18.2.1 2011/06/23 14:19:50 cherry Exp $      */
+/*      $NetBSD: xengnt.c,v 1.18.2.2 2011/09/04 01:15:13 mhitch Exp $      */
 
 /*
  * Copyright (c) 2006 Manuel Bouyer.
@@ -26,7 +26,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.18.2.1 2011/06/23 14:19:50 cherry Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.18.2.2 2011/09/04 01:15:13 mhitch Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -35,6 +35,7 @@
 #include <sys/queue.h>
 #include <sys/extent.h>
 #include <sys/kernel.h>
+#include <sys/mutex.h>
 #include <uvm/uvm.h>
 
 #include <xen/hypervisor.h>
@@ -62,6 +63,8 @@
 /* empty entry in the list */
 #define XENGNT_NO_ENTRY 0xffffffff
 
+static kmutex_t        gnt_mutex;
+
 /* VM address of the grant table */
 grant_entry_t *grant_table;
 
@@ -101,6 +104,7 @@
                gnt_entries[i] = XENGNT_NO_ENTRY;
 
        last_gnt_entry = 0;
+       mutex_init(&gnt_mutex, MUTEX_DEFAULT, IPL_VM);
        xengnt_resume();
 
 }
@@ -192,13 +196,13 @@
 xengnt_get_entry(void)
 {
        grant_ref_t entry;
-       int s = splvm();
        static struct timeval xengnt_nonmemtime;
        static const struct timeval xengnt_nonmemintvl = {5,0};
 
+       mutex_enter(&gnt_mutex);
        if (last_gnt_entry == 0) {
                if (xengnt_more_entries()) {
-                       splx(s);
+                       mutex_exit(&gnt_mutex);
                        if (ratecheck(&xengnt_nonmemtime, &xengnt_nonmemintvl))
                                printf("xengnt_get_entry: out of grant "
                                    "table entries\n");
@@ -209,7 +213,7 @@
        last_gnt_entry--;
        entry = gnt_entries[last_gnt_entry];
        gnt_entries[last_gnt_entry] = XENGNT_NO_ENTRY;
-       splx(s);
+       mutex_exit(&gnt_mutex);
        KASSERT(entry != XENGNT_NO_ENTRY);
        KASSERT(last_gnt_entry >= 0);
        KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE);
@@ -222,13 +226,13 @@
 static void
 xengnt_free_entry(grant_ref_t entry)
 {
-       int s = splvm();
+       mutex_enter(&gnt_mutex);
        KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY);
        KASSERT(last_gnt_entry >= 0);
        KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE);
        gnt_entries[last_gnt_entry] = entry;
        last_gnt_entry++;
-       splx(s);
+       mutex_exit(&gnt_mutex);
 }
 
 int