[SCSI] libiscsi: check that command ptr is set before accessing it

If the scsi eh sends a TUR and the session is down we could
return SCSI_ML_HOST_BUSY. scsi eh will ignore this and send
ask us to abort the command and we blindly accesst the
command ptr.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libiscsi.c

@@ -192,6 +192,8 @@ static void iscsi_complete_command(struct iscsi_cmd_task *ctask)
 
 	ctask->state = ISCSI_TASK_COMPLETED;
 	ctask->sc = NULL;
+	/* SCSI eh reuses commands to verify us */
+	sc->SCp.ptr = NULL;
 	list_del_init(&ctask->running);
 	__kfifo_put(session->cmdpool.queue, (void*)&ctask, sizeof(void*));
 	sc->scsi_done(sc);
@@ -737,6 +739,7 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 
 	sc->scsi_done = done;
 	sc->result = 0;
+	sc->SCp.ptr = NULL;
 
 	host = sc->device->host;
 	session = iscsi_hostdata(host->hostdata);
@@ -801,9 +804,10 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 
 	list_add_tail(&ctask->running, &conn->xmitqueue);
 	debug_scsi(
-	       "ctask enq [%s cid %d sc %lx itt 0x%x len %d cmdsn %d win %d]\n",
+	       "ctask enq [%s cid %d sc %p cdb 0x%x itt 0x%x len %d cmdsn %d "
+		"win %d]\n",
 		sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
-		conn->id, (long)sc, ctask->itt, sc->request_bufflen,
+		conn->id, sc, sc->cmnd[0], ctask->itt, sc->request_bufflen,
 		session->cmdsn, session->max_cmdsn - session->exp_cmdsn + 1);
 	spin_unlock(&session->lock);
 
@@ -1134,11 +1138,24 @@ static void fail_command(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 
 int iscsi_eh_abort(struct scsi_cmnd *sc)
 {
-	struct iscsi_cmd_task *ctask = (struct iscsi_cmd_task *)sc->SCp.ptr;
-	struct iscsi_conn *conn = ctask->conn;
-	struct iscsi_session *session = conn->session;
+	struct iscsi_cmd_task *ctask;
+	struct iscsi_conn *conn;
+	struct iscsi_session *session;
 	int rc;
 
+	/*
+	 * if session was ISCSI_STATE_IN_RECOVERY then we may not have
+	 * got the command.
+	 */
+	if (!sc->SCp.ptr) {
+		debug_scsi("sc never reached iscsi layer or it completed.\n");
+		return SUCCESS;
+	}
+
+	ctask = (struct iscsi_cmd_task *)sc->SCp.ptr;
+	conn = ctask->conn;
+	session = conn->session;
+
 	conn->eh_abort_cnt++;
 	debug_scsi("aborting [sc %p itt 0x%x]\n", sc, ctask->itt);