[Qemu-devel] [PATCH] iscsi: fix deadlock during login

[Peter Lieven <pl@dlhnet.de>]

If the connection is interrupted before the first login is successfully
completed qemu-kvm is waiting forever in qemu_aio_wait().

This is fixed by performing an sync login to the target. If the
connection breaks after the first successful login errors are
handled internally by libiscsi.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
  block/iscsi.c |   56 
+++++++++++++++++++++-----------------------------------
  1 file changed, 21 insertions(+), 35 deletions(-)

diff --git a/block/iscsi.c b/block/iscsi.c
index b5c3161..f44bb57 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -798,30 +798,6 @@ iscsi_inquiry_cb(struct iscsi_context *iscsi, int 
status, void *command_data,
      }
  }

-static void
-iscsi_connect_cb(struct iscsi_context *iscsi, int status, void 
*command_data,
-                 void *opaque)
-{
-    struct IscsiTask *itask = opaque;
-    struct scsi_task *task;
-
-    if (status != 0) {
-        itask->status   = 1;
-        itask->complete = 1;
-        return;
-    }
-
-    task = iscsi_inquiry_task(iscsi, itask->iscsilun->lun,
-                              0, 0, 36,
-                              iscsi_inquiry_cb, opaque);
-    if (task == NULL) {
-        error_report("iSCSI: failed to send inquiry command.");
-        itask->status   = 1;
-        itask->complete = 1;
-        return;
-    }
-}
-
  static int parse_chap(struct iscsi_context *iscsi, const char *target)
  {
      QemuOptsList *list;
@@ -934,7 +910,8 @@ static int iscsi_open(BlockDriverState *bs, const 
char *filename, int flags)
      IscsiLun *iscsilun = bs->opaque;
      struct iscsi_context *iscsi = NULL;
      struct iscsi_url *iscsi_url = NULL;
-    struct IscsiTask task;
+    struct IscsiTask itask;
+    struct scsi_task *task;
      char *initiator_name = NULL;
      int ret;

@@ -997,27 +974,36 @@ static int iscsi_open(BlockDriverState *bs, const 
char *filename, int flags)
      /* check if we got HEADER_DIGEST via the options */
      parse_header_digest(iscsi, iscsi_url->target);

-    task.iscsilun = iscsilun;
-    task.status = 0;
-    task.complete = 0;
-    task.bs = bs;
+    if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, 
iscsi_url->lun) != 0) {
+        error_report("iSCSI: Failed to connect to LUN : %s",
+            iscsi_get_error(iscsi));
+        ret = -EINVAL;
+        goto out;
+    }
+
+    itask.iscsilun = iscsilun;
+    itask.status = 0;
+    itask.complete = 0;
+    itask.bs = bs;

      iscsilun->iscsi = iscsi;
      iscsilun->lun   = iscsi_url->lun;

-    if (iscsi_full_connect_async(iscsi, iscsi_url->portal, iscsi_url->lun,
-                                 iscsi_connect_cb, &task)
-        != 0) {
-        error_report("iSCSI: Failed to start async connect.");
+    task = iscsi_inquiry_task(iscsi, iscsilun->lun,
+                              0, 0, 36,
+                              iscsi_inquiry_cb, &itask);
+    if (task == NULL) {
+        error_report("iSCSI: failed to send inquiry command.");
          ret = -EINVAL;
          goto out;
      }

-    while (!task.complete) {
+    while (!itask.complete) {
          iscsi_set_events(iscsilun);
          qemu_aio_wait();
      }
-    if (task.status != 0) {
+
+    if (itask.status != 0) {
          error_report("iSCSI: Failed to connect to LUN : %s",
                       iscsi_get_error(iscsi));
          ret = -EINVAL;
-- 
1.7.9.5