[src/trunk]: src/sys/arch/xen/xen Avoid overrun problems with the indexes of ...

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

details:   https://anonhg.NetBSD.org/src/rev/92e59abfdd5d
branches:  trunk
changeset: 566461:92e59abfdd5d
user:      cl <cl%NetBSD.org@localhost>
date:      Mon May 10 01:39:39 2004 +0000

description:
Avoid overrun problems with the indexes of the slots in the
communication rings.

diffstat:

 sys/arch/xen/xen/xbd.c |  24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)

diffs (87 lines):

diff -r 3c7f30b8476b -r 92e59abfdd5d sys/arch/xen/xen/xbd.c
--- a/sys/arch/xen/xen/xbd.c    Mon May 10 01:34:59 2004 +0000
+++ b/sys/arch/xen/xen/xbd.c    Mon May 10 01:39:39 2004 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: xbd.c,v 1.8 2004/05/07 14:15:11 cl Exp $ */
+/* $NetBSD: xbd.c,v 1.9 2004/05/10 01:39:39 cl Exp $ */
 
 /*
  *
@@ -33,7 +33,7 @@
 
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xbd.c,v 1.8 2004/05/07 14:15:11 cl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xbd.c,v 1.9 2004/05/10 01:39:39 cl Exp $");
 
 #include "xbd.h"
 
@@ -351,6 +351,7 @@
 static blk_ring_t *blk_ring = NULL;
 static BLK_RING_IDX resp_cons; /* Response consumer for comms ring. */
 static BLK_RING_IDX req_prod;  /* Private request producer.         */
+static BLK_RING_IDX last_req_prod;  /* Request producer at last trap. */
 
 #define STATE_ACTIVE    0
 #define STATE_SUSPENDED 1
@@ -448,7 +449,7 @@
                    blk_ring, (void *)(op.u.ring_mfn << PAGE_SHIFT)));
 
                blk_ring->req_prod = blk_ring->resp_prod =
-                       resp_cons = req_prod = 0;
+                       resp_cons = req_prod = last_req_prod = 0;
 
                event_set_handler(_EVENT_BLKDEV, &xbd_response_handler,
                    NULL, IPL_BIO);
@@ -474,8 +475,9 @@
        block_io_op_t op; 
 
        DPRINTF(XBDB_IO, ("signal_requests_to_xen: %d -> %d\n",
-           blk_ring->req_prod, req_prod));
-       blk_ring->req_prod = req_prod;
+           blk_ring->req_prod, MASK_BLK_IDX(req_prod)));
+       blk_ring->req_prod = MASK_BLK_IDX(req_prod);
+       last_req_prod = req_prod;
 
        op.cmd = BLOCK_IO_OP_SIGNAL; 
        HYPERVISOR_block_io_op(&op);
@@ -597,7 +599,11 @@
        xbd_allxr = xr;
 #endif
 
-       for (i = 0; i < BLK_RING_SIZE; i++)
+       /* XXX Xen1.2: We cannot use BLK_RING_SIZE many slots, since
+        * Xen 1.2 keeps indexes masked in the ring and the case where
+        * we queue all slots at once is handled wrong. 
+        */
+       for (i = 0; i < BLK_RING_SIZE - 1; i++)
                PUT_XBDREQ(&xr[i]);
 
        MALLOC(vbd_info, xen_disk_t *, MAX_VBDS * sizeof(xen_disk_t),
@@ -893,7 +899,7 @@
        }
        pxr->xr_data = addr;
 
-       req_prod = BLK_RING_INC(req_prod);
+       req_prod++;
 }
 
 static void
@@ -1031,7 +1037,7 @@
        }
 
  out:
-       if (runqueue && blk_ring->req_prod != req_prod)
+       if (runqueue && last_req_prod != req_prod)
                signal_requests_to_xen();
 
        return ret;
@@ -1104,7 +1110,7 @@
        }
        resp_cons = i;
        /* check if xbdresume queued any requests */
-       if (blk_ring->req_prod != req_prod)
+       if (last_req_prod != req_prod)
                signal_requests_to_xen();
        return 0;
 }