Revert "iscsi: Fix NULL dereferences / races between task completion and abort"
This reverts commit 64e69e80920d82df3fa679bc41b13770d2f99360. The commit
returned immediately from iscsi_aio_cancel, risking corruption in case the
following happens:
guest qemu target
=========================================================================
send write 1 -------->
send write 1 -------->
cancel write 1 ------>
cancel write 1 ------>
<------------------ cancellation processed
send write 2 -------->
send write 2 -------->
<---------------- completed write 2
<------------------ completed write 2
<---------------- completed write 1
<---------------- cancellation not done
Here, the guest would see write 2 superseding write 1, when in fact the
outcome could have been the opposite. The right behavior is to return
only after the target says whether the cancellation was done or not, and
it will be implemented by the next three patches.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/block/iscsi.c b/block/iscsi.c
index bb9cf82..219f927 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -76,10 +76,6 @@
iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data,
void *private_data)
{
- IscsiAIOCB *acb = (IscsiAIOCB *)private_data;
-
- scsi_free_scsi_task(acb->task);
- acb->task = NULL;
}
static void
@@ -88,15 +84,15 @@
IscsiAIOCB *acb = (IscsiAIOCB *)blockacb;
IscsiLun *iscsilun = acb->iscsilun;
+ acb->common.cb(acb->common.opaque, -ECANCELED);
acb->canceled = 1;
- acb->common.cb(acb->common.opaque, -ECANCELED);
-
- /* send a task mgmt call to the target to cancel the task on the target
- * this also cancels the task in libiscsi
- */
+ /* send a task mgmt call to the target to cancel the task on the target */
iscsi_task_mgmt_abort_task_async(iscsilun->iscsi, acb->task,
- iscsi_abort_task_cb, &acb);
+ iscsi_abort_task_cb, NULL);
+
+ /* then also cancel the task locally in libiscsi */
+ iscsi_scsi_task_cancel(iscsilun->iscsi, acb->task);
}
static AIOPool iscsi_aio_pool = {
@@ -183,18 +179,11 @@
qemu_bh_delete(acb->bh);
- if (!acb->canceled) {
+ if (acb->canceled == 0) {
acb->common.cb(acb->common.opaque, acb->status);
}
qemu_aio_release(acb);
-
- if (acb->canceled) {
- return;
- }
-
- scsi_free_scsi_task(acb->task);
- acb->task = NULL;
}
@@ -208,8 +197,10 @@
g_free(acb->buf);
- if (acb->canceled) {
+ if (acb->canceled != 0) {
qemu_aio_release(acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
return;
}
@@ -221,6 +212,8 @@
}
iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
}
static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
@@ -305,8 +298,10 @@
trace_iscsi_aio_read16_cb(iscsi, status, acb, acb->canceled);
- if (acb->canceled) {
+ if (acb->canceled != 0) {
qemu_aio_release(acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
return;
}
@@ -318,6 +313,8 @@
}
iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
}
static BlockDriverAIOCB *
@@ -417,8 +414,10 @@
{
IscsiAIOCB *acb = opaque;
- if (acb->canceled) {
+ if (acb->canceled != 0) {
qemu_aio_release(acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
return;
}
@@ -430,6 +429,8 @@
}
iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
}
static BlockDriverAIOCB *
@@ -467,8 +468,10 @@
{
IscsiAIOCB *acb = opaque;
- if (acb->canceled) {
+ if (acb->canceled != 0) {
qemu_aio_release(acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
return;
}
@@ -480,6 +483,8 @@
}
iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
}
static BlockDriverAIOCB *
@@ -523,8 +528,10 @@
{
IscsiAIOCB *acb = opaque;
- if (acb->canceled) {
+ if (acb->canceled != 0) {
qemu_aio_release(acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
return;
}
@@ -553,6 +560,8 @@
}
iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
+ scsi_free_scsi_task(acb->task);
+ acb->task = NULL;
}
static BlockDriverAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
