[Qemu-devel] [PULL 15/35] block/iscsi: cancel libiscsi task when ABORT TASK TMF completes

[Paolo Bonzini <pbonzini@redhat.com>]

From: Stefan Hajnoczi <stefanha@redhat.com>

The libiscsi iscsi_task_mgmt_async() API documentation says:

  abort_task will also cancel the scsi task. The callback for the scsi
  task will be invoked with SCSI_STATUS_CANCELLED

The libiscsi implementation does not fulfil this promise.  The task's
callback is not invoked and its struct iscsi_pdu remains in the internal
list (effectively leaked).

This patch invokes the libiscsi iscsi_scsi_cancel_task() API to force
the task's callback to be invoked with SCSI_STATUS_CANCELLED when the
ABORT TASK TMF completes and the task's callback hasn't been invoked
yet.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20180215111526.2464-1-stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/iscsi.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/iscsi.c b/block/iscsi.c
index abb872d3d9..a7e8c1ffaf 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -295,8 +295,12 @@ iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data,
 {
     IscsiAIOCB *acb = private_data;
 
-    acb->status = -ECANCELED;
-    iscsi_schedule_bh(acb);
+    /* If the command callback hasn't been called yet, drop the task */
+    if (!acb->bh) {
+        /* Call iscsi_aio_ioctl_cb() with SCSI_STATUS_CANCELLED */
+        iscsi_scsi_cancel_task(iscsi, acb->task);
+    }
+
     qemu_aio_unref(acb); /* acquired in iscsi_aio_cancel() */
 }
 
@@ -947,6 +951,14 @@ iscsi_aio_ioctl_cb(struct iscsi_context *iscsi, int status,
 {
     IscsiAIOCB *acb = opaque;
 
+    if (status == SCSI_STATUS_CANCELLED) {
+        if (!acb->bh) {
+            acb->status = -ECANCELED;
+            iscsi_schedule_bh(acb);
+        }
+        return;
+    }
+
     acb->status = 0;
     if (status < 0) {
         error_report("Failed to ioctl(SG_IO) to iSCSI lun. %s",
-- 
2.20.1