From patchwork Tue Dec 1 23:38:34 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: vmstate: Avoid seeking Date: Tue, 01 Dec 2009 13:38:34 -0000 From: Jan Kiszka X-Patchwork-Id: 39937 Message-Id: <4B15A8FA.5080804@web.de> To: Anthony Liguori Cc: Pierre Riteau , qemu-devel , Liran Schour , Juan Quintela 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 Acked-by: Ryan Harper --- 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 = {