scsi: qedf: Add more defensive checks for concurrent error conditions

During an uplink toggle test all error handling is done via timeout and
firmware error conditions which can occur concurrently:

 - SCSI layer timeouts
 - Error detect CQEs
 - Firmware detected underruns
 - ABTS timeouts

All these concurrent events require more defensive checks in the driver
including:

 - Check both internally and externally generated aborts to make sure the
   xid is not already been aborted in another context or in cleanup.

 - Check back pointers in qedf_cmd_timeout to verify the context of the
   io_req, fcport and qedf_ctx

 - Check rport state in host reset handler to not reset the whole host
   if the rport is already uploaded or in the process of relogin

 - Check to state for an fcport before initiating a middle path ELS
   request
Signed-off-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qedf/qedf_els.c

@@ -14,8 +14,8 @@ static int qedf_initiate_els(struct qedf_rport *fcport, unsigned int op,
 	void (*cb_func)(struct qedf_els_cb_arg *cb_arg),
 	struct qedf_els_cb_arg *cb_arg, uint32_t timer_msec)
 {
-	struct qedf_ctx *qedf = fcport->qedf;
-	struct fc_lport *lport = qedf->lport;
+	struct qedf_ctx *qedf;
+	struct fc_lport *lport;
 	struct qedf_ioreq *els_req;
 	struct qedf_mp_req *mp_req;
 	struct fc_frame_header *fc_hdr;
@@ -29,6 +29,15 @@ static int qedf_initiate_els(struct qedf_rport *fcport, unsigned int op,
 	unsigned long flags;
 	u16 sqe_idx;
 
+	if (!fcport) {
+		QEDF_ERR(NULL, "fcport is NULL");
+		rc = -EINVAL;
+		goto els_err;
+	}
+
+	qedf = fcport->qedf;
+	lport = qedf->lport;
+
 	QEDF_INFO(&(qedf->dbg_ctx), QEDF_LOG_ELS, "Sending ELS\n");
 
 	rc = fc_remote_port_chkready(fcport->rport);

drivers/scsi/qedf/qedf_io.c

@@ -23,12 +23,31 @@ static void qedf_cmd_timeout(struct work_struct *work)
 
 	struct qedf_ioreq *io_req =
 	    container_of(work, struct qedf_ioreq, timeout_work.work);
-	struct qedf_ctx *qedf = io_req->fcport->qedf;
-	struct qedf_rport *fcport = io_req->fcport;
+	struct qedf_ctx *qedf;
+	struct qedf_rport *fcport;
 	u8 op = 0;
 
+	if (io_req == NULL) {
+		QEDF_INFO(NULL, QEDF_LOG_IO, "io_req is NULL.\n");
+		return;
+	}
+
+	fcport = io_req->fcport;
+	if (io_req->fcport == NULL) {
+		QEDF_INFO(NULL, QEDF_LOG_IO,  "fcport is NULL.\n");
+		return;
+	}
+
+	qedf = fcport->qedf;
+
 	switch (io_req->cmd_type) {
 	case QEDF_ABTS:
+		if (qedf == NULL) {
+			QEDF_INFO(NULL, QEDF_LOG_IO, "qedf is NULL for xid=0x%x.\n",
+			    io_req->xid);
+			return;
+		}
+
 		QEDF_ERR((&qedf->dbg_ctx), "ABTS timeout, xid=0x%x.\n",
 		    io_req->xid);
 		/* Cleanup timed out ABTS */
@@ -1565,6 +1584,16 @@ int qedf_initiate_abts(struct qedf_ioreq *io_req, bool return_scsi_cmd_on_abts)
 		goto out;
 	}
 
+	if (!test_bit(QEDF_CMD_OUTSTANDING, &io_req->flags) ||
+	    test_bit(QEDF_CMD_IN_CLEANUP, &io_req->flags) ||
+	    test_bit(QEDF_CMD_IN_ABORT, &io_req->flags)) {
+		QEDF_ERR(&(qedf->dbg_ctx), "io_req xid=0x%x already in "
+			  "cleanup or abort processing or already "
+			  "completed.\n", io_req->xid);
+		rc = 1;
+		goto out;
+	}
+
 	kref_get(&io_req->refcount);
 
 	xid = io_req->xid;

drivers/scsi/qedf/qedf_main.c

@@ -643,16 +643,6 @@ static int qedf_eh_abort(struct scsi_cmnd *sc_cmd)
 		goto out;
 	}
 
-	if (!test_bit(QEDF_CMD_OUTSTANDING, &io_req->flags) ||
-	    test_bit(QEDF_CMD_IN_CLEANUP, &io_req->flags) ||
-	    test_bit(QEDF_CMD_IN_ABORT, &io_req->flags)) {
-		QEDF_ERR(&(qedf->dbg_ctx), "io_req xid=0x%x already in "
-			  "cleanup or abort processing or already "
-			  "completed.\n", io_req->xid);
-		rc = SUCCESS;
-		goto out;
-	}
-
 	QEDF_ERR(&(qedf->dbg_ctx), "Aborting io_req sc_cmd=%p xid=0x%x "
 		  "fp_idx=%d.\n", sc_cmd, io_req->xid, io_req->fp_idx);
 
@@ -748,6 +738,22 @@ static int qedf_eh_host_reset(struct scsi_cmnd *sc_cmd)
 {
 	struct fc_lport *lport;
 	struct qedf_ctx *qedf;
+	struct fc_rport *rport = starget_to_rport(scsi_target(sc_cmd->device));
+	struct fc_rport_libfc_priv *rp = rport->dd_data;
+	struct qedf_rport *fcport = (struct qedf_rport *)&rp[1];
+	int rval;
+
+	rval = fc_remote_port_chkready(rport);
+
+	if (rval) {
+		QEDF_ERR(NULL, "device_reset rport not ready\n");
+		return FAILED;
+	}
+
+	if (fcport == NULL) {
+		QEDF_ERR(NULL, "device_reset: rport is NULL\n");
+		return FAILED;
+	}
 
 	lport = shost_priv(sc_cmd->device->host);
 	qedf = lport_priv(lport);