iscsi: fix leak of task for delayed management request

Fix the following crash of tgtd which occured when removing a target
with --force option:

  conn_close(90) already closed 0x2058598 1
  iscsi_target_destroy(416) bug still have sessions 91

This crash happens if a task remains after the following calls of
conn_close() function for every connection on the target.

  list_for_each_entry_safe(session, stmp, &target->sessions_list, slist) {
          list_for_each_entry_safe(conn, ctmp, &session->conn_list, clist) {
                  conn_close(conn);
          }
  }

The leaked task turned out to be a task for handling ABORT_TASK
management request which was delayed due to a flying io.  The delayed
management request is attached to cmd->mreq of the io command and is
completed by iscsi_tm_done() function.  However, this function fails
with the following error and leaks the task if associated connection
(task->conn) is already closed:

 tgt_event_modify(245) Cannot find event 25
 iscsi_event_modify(560) tgt_event_modify failed

This fixes the issue by freeing task in iscsi_tm_done() if state of
the connection is STATE_CLOSE.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
iscsi: fix segfault at iscsi_scsi_cmd_done()

When enabling ping-nop of iscsi by setting valid values to
nop_interval and nop_count parameters, tgtd crashed with the following
segmentation fault at iscsi_scsi_cmd_done() function:

 Program terminated with signal 11, Segmentation fault.
 #0  __list_add (nid=<value optimized out>, result=<value optimized out>,
     scmd=0x980f20) at ./list.h:67
 67              prev->next = new;
 (gdb) bt
 #0  __list_add (nid=<value optimized out>, result=<value optimized out>,
     scmd=0x980f20) at ./list.h:67
 #1  list_add_tail (nid=<value optimized out>, result=<value optimized out>,
     scmd=0x980f20) at ./list.h:77
 #2  iscsi_scsi_cmd_done (nid=<value optimized out>,
     result=<value optimized out>, scmd=0x980f20) at iscsi/iscsid.c:1270
 #3  0x000000000042b69d in bs_sig_request_done (fd=<value optimized out>,
     events=<value optimized out>, data=<value optimized out>) at bs.c:212
 #4  0x0000000000414231 in event_loop () at tgtd.c:432
 #5  0x000000000041490a in main (argc=<value optimized out>,
     argv=<value optimized out>) at tgtd.c:620

This segfault is caused by forcible destruction of tcp connection
using iscsi_tcp_release() within iscsi_tcp_nop_work_handler().

This patch fixes it by closing connection cleanly there with
conn_close() function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Fix segfault if device_type set to pt but bstype not sg or bsg

If bstype not set to sg or bsg, it will default to rdwr, and we will
call target_cmd_perform instead of target_cmd_perform_passthrough when
accessing the device, which crashes tgtd. There's an existing check for
setting bstype without setting dev_type, but also add a check the other
way, setting dev_type without setting bstype to a valid value for pt.

Add an error message to the existing check, as well.

Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>