[PATCH v2 20/28] scsi: qedi: Fix race during abort timeouts

[Mike Christie <michael.christie@oracle.com>]

If the SCSI cmd completes after qedi_tmf_work calls iscsi_itt_to_task then
the qedi qedi_cmd->task_id could be freed and used for another cmd. If we
then call qedi_iscsi_cleanup_task with that task_id we will be cleaning up
the wrong cmd.

This patch has us wait to release the task_id until the last put has been
done on the iscsi_task. Because libiscsi grabs a ref to the task when
sending the abort, we know that for the non abort timeout case that the
task_id we are referencing is for the cmd that was supposed to be aborted.

The next patch will fix the case where the abort timesout while we are
running qedi_tmf_work.

Reviewed-by: Manish Rangankar <mrangankar@marvell.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/qedi/qedi_fw.c    | 15 ---------------
 drivers/scsi/qedi/qedi_iscsi.c | 20 +++++++++++++++++---
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/drivers/scsi/qedi/qedi_fw.c b/drivers/scsi/qedi/qedi_fw.c
index cf57b4e49700..c12bb2dd5ff9 100644
--- a/drivers/scsi/qedi/qedi_fw.c
+++ b/drivers/scsi/qedi/qedi_fw.c
@@ -73,7 +73,6 @@ static void qedi_process_logout_resp(struct qedi_ctx *qedi,
 	spin_unlock(&qedi_conn->list_lock);
 
 	cmd->state = RESPONSE_RECEIVED;
-	qedi_clear_task_idx(qedi, cmd->task_id);
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)resp_hdr, NULL, 0);
 
 	spin_unlock(&session->back_lock);
@@ -138,7 +137,6 @@ static void qedi_process_text_resp(struct qedi_ctx *qedi,
 	spin_unlock(&qedi_conn->list_lock);
 
 	cmd->state = RESPONSE_RECEIVED;
-	qedi_clear_task_idx(qedi, cmd->task_id);
 
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)resp_hdr_ptr,
 			     qedi_conn->gen_pdu.resp_buf,
@@ -164,13 +162,11 @@ static void qedi_tmf_resp_work(struct work_struct *work)
 	iscsi_block_session(session->cls_session);
 	rval = qedi_cleanup_all_io(qedi, qedi_conn, qedi_cmd->task, true);
 	if (rval) {
-		qedi_clear_task_idx(qedi, qedi_cmd->task_id);
 		iscsi_unblock_session(session->cls_session);
 		goto exit_tmf_resp;
 	}
 
 	iscsi_unblock_session(session->cls_session);
-	qedi_clear_task_idx(qedi, qedi_cmd->task_id);
 
 	spin_lock(&session->back_lock);
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)resp_hdr_ptr, NULL, 0);
@@ -245,8 +241,6 @@ static void qedi_process_tmf_resp(struct qedi_ctx *qedi,
 		goto unblock_sess;
 	}
 
-	qedi_clear_task_idx(qedi, qedi_cmd->task_id);
-
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)resp_hdr_ptr, NULL, 0);
 	kfree(resp_hdr_ptr);
 
@@ -314,7 +308,6 @@ static void qedi_process_login_resp(struct qedi_ctx *qedi,
 		  "Freeing tid=0x%x for cid=0x%x\n",
 		  cmd->task_id, qedi_conn->iscsi_conn_id);
 	cmd->state = RESPONSE_RECEIVED;
-	qedi_clear_task_idx(qedi, cmd->task_id);
 }
 
 static void qedi_get_rq_bdq_buf(struct qedi_ctx *qedi,
@@ -468,7 +461,6 @@ static int qedi_process_nopin_mesg(struct qedi_ctx *qedi,
 		}
 
 		spin_unlock(&qedi_conn->list_lock);
-		qedi_clear_task_idx(qedi, cmd->task_id);
 	}
 
 done:
@@ -673,7 +665,6 @@ static void qedi_scsi_completion(struct qedi_ctx *qedi,
 	if (qedi_io_tracing)
 		qedi_trace_io(qedi, task, cmd->task_id, QEDI_IO_TRACE_RSP);
 
-	qedi_clear_task_idx(qedi, cmd->task_id);
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)hdr,
 			     conn->data, datalen);
 error:
@@ -730,7 +721,6 @@ static void qedi_process_nopin_local_cmpl(struct qedi_ctx *qedi,
 		  cqe->itid, cmd->task_id);
 
 	cmd->state = RESPONSE_RECEIVED;
-	qedi_clear_task_idx(qedi, cmd->task_id);
 
 	spin_lock_bh(&session->back_lock);
 	__iscsi_put_task(task);
@@ -748,7 +738,6 @@ static void qedi_process_cmd_cleanup_resp(struct qedi_ctx *qedi,
 	itt_t protoitt = 0;
 	int found = 0;
 	struct qedi_cmd *qedi_cmd = NULL;
-	u32 rtid = 0;
 	u32 iscsi_cid;
 	struct qedi_conn *qedi_conn;
 	struct qedi_cmd *dbg_cmd;
@@ -779,7 +768,6 @@ static void qedi_process_cmd_cleanup_resp(struct qedi_ctx *qedi,
 			found = 1;
 			mtask = qedi_cmd->task;
 			tmf_hdr = (struct iscsi_tm *)mtask->hdr;
-			rtid = work->rtid;
 
 			list_del_init(&work->list);
 			kfree(work);
@@ -821,8 +809,6 @@ static void qedi_process_cmd_cleanup_resp(struct qedi_ctx *qedi,
 			if (qedi_cmd->state == CLEANUP_WAIT_FAILED)
 				qedi_cmd->state = CLEANUP_RECV;
 
-			qedi_clear_task_idx(qedi_conn->qedi, rtid);
-
 			spin_lock(&qedi_conn->list_lock);
 			if (likely(dbg_cmd->io_cmd_in_list)) {
 				dbg_cmd->io_cmd_in_list = false;
@@ -856,7 +842,6 @@ static void qedi_process_cmd_cleanup_resp(struct qedi_ctx *qedi,
 		QEDI_INFO(&qedi->dbg_ctx, QEDI_LOG_TID,
 			  "Freeing tid=0x%x for cid=0x%x\n",
 			  cqe->itid, qedi_conn->iscsi_conn_id);
-		qedi_clear_task_idx(qedi_conn->qedi, cqe->itid);
 
 	} else {
 		qedi_get_proto_itt(qedi, cqe->itid, &ptmp_itt);
diff --git a/drivers/scsi/qedi/qedi_iscsi.c b/drivers/scsi/qedi/qedi_iscsi.c
index 80f8d35b5900..5304a028db0a 100644
--- a/drivers/scsi/qedi/qedi_iscsi.c
+++ b/drivers/scsi/qedi/qedi_iscsi.c
@@ -783,7 +783,6 @@ static int qedi_mtask_xmit(struct iscsi_conn *conn, struct iscsi_task *task)
 	}
 
 	cmd->conn = conn->dd_data;
-	cmd->scsi_cmd = NULL;
 	return qedi_iscsi_send_generic_request(task);
 }
 
@@ -794,6 +793,10 @@ static int qedi_task_xmit(struct iscsi_task *task)
 	struct qedi_cmd *cmd = task->dd_data;
 	struct scsi_cmnd *sc = task->sc;
 
+	/* Clear now so in cleanup_task we know it didn't make it */
+	cmd->scsi_cmd = NULL;
+	cmd->task_id = U16_MAX;
+
 	if (test_bit(QEDI_IN_SHUTDOWN, &qedi_conn->qedi->flags))
 		return -ENODEV;
 
@@ -1391,13 +1394,24 @@ static umode_t qedi_attr_is_visible(int param_type, int param)
 
 static void qedi_cleanup_task(struct iscsi_task *task)
 {
-	if (!task->sc || task->state == ISCSI_TASK_PENDING) {
+	struct qedi_cmd *cmd;
+
+	if (task->state == ISCSI_TASK_PENDING) {
 		QEDI_INFO(NULL, QEDI_LOG_IO, "Returning ref_cnt=%d\n",
 			  refcount_read(&task->refcount));
 		return;
 	}
 
-	qedi_iscsi_unmap_sg_list(task->dd_data);
+	if (task->sc)
+		qedi_iscsi_unmap_sg_list(task->dd_data);
+
+	cmd = task->dd_data;
+	if (cmd->task_id != U16_MAX)
+		qedi_clear_task_idx(iscsi_host_priv(task->conn->session->host),
+				    cmd->task_id);
+
+	cmd->task_id = U16_MAX;
+	cmd->scsi_cmd = NULL;
 }
 
 struct iscsi_transport qedi_iscsi_transport = {
-- 
2.25.1