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[Qemu-devel] [PATCH] vmstate: Avoid seeking
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] [PATCH] vmstate: Avoid seeking |
Date: |
Wed, 02 Dec 2009 00:38:34 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Seeking on vmstate save/load does not work if the underlying file is a
stream. We could try to make all QEMUFile* forward-seek-aware, but first
attempts in this direction indicated that it's saner to convert the few
qemu_fseek-on-vmstates users to plain reads/writes.
This fixes various subtle vmstate corruptions where unused fields were
involved.
Signed-off-by: Jan Kiszka <address@hidden>
---
hw/virtio-net.c | 7 ++-----
savevm.c | 18 ++++++++++++++++--
2 files changed, 18 insertions(+), 7 deletions(-)
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 2f147e5..9ccd4c8 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -745,12 +745,9 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int
version_id)
if (version_id >= 5) {
n->mac_table.in_use = qemu_get_be32(f);
+ qemu_get_buffer(f, n->mac_table.macs, n->mac_table.in_use * ETH_ALEN);
/* MAC_TABLE_ENTRIES may be different from the saved image */
- if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {
- qemu_get_buffer(f, n->mac_table.macs,
- n->mac_table.in_use * ETH_ALEN);
- } else if (n->mac_table.in_use) {
- qemu_fseek(f, n->mac_table.in_use * ETH_ALEN, SEEK_CUR);
+ if (n->mac_table.in_use > MAC_TABLE_ENTRIES) {
n->mac_table.multi_overflow = n->mac_table.uni_overflow = 1;
n->mac_table.in_use = 0;
}
diff --git a/savevm.c b/savevm.c
index 8fe9349..1e54a42 100644
--- a/savevm.c
+++ b/savevm.c
@@ -959,13 +959,27 @@ const VMStateInfo vmstate_info_buffer = {
static int get_unused_buffer(QEMUFile *f, void *pv, size_t size)
{
- qemu_fseek(f, size, SEEK_CUR);
+ uint8_t buf[1024];
+ int block_len;
+
+ while (size > 0) {
+ block_len = MIN(sizeof(buf), size);
+ size -= block_len;
+ qemu_get_buffer(f, buf, block_len);
+ }
return 0;
}
static void put_unused_buffer(QEMUFile *f, void *pv, size_t size)
{
- qemu_fseek(f, size, SEEK_CUR);
+ static const uint8_t buf[1024];
+ int block_len;
+
+ while (size > 0) {
+ block_len = MIN(sizeof(buf), size);
+ size -= block_len;
+ qemu_put_buffer(f, buf, block_len);
+ }
}
const VMStateInfo vmstate_info_unused_buffer = {
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- [Qemu-devel] [PATCH] vmstate: Avoid seeking,
Jan Kiszka <=