scsi: lpfc: Rework remote port ref counting and node freeing

When a remote port is disconnected and disappears, its node structure
(ndlp) stays allocated and on a vport node list. While on the list it can
be matched, thus requires validation checks on state to be added in
numerous code paths. If the node comes back, its possible for there to be
multiple node structures for the same device on the vport node list. There
is no reason to keep the node structure around after it is no longer in
existence, and the current implementation creates problems for itself
(multiple nodes) and lots of unnecessary code for state validation.

Additionally, the reference taking on the node structure didn't follow the
normal model used by the kernel kref api. It included lots of odd logic to
match state with reference count.  The combination of this odd logic plus
the way it was implicitly used in the discovery engine made its reference
taking implementation suspect and extremely hard to follow.

Change the driver such that the reference taking routines are now normal
ref increments/decrements and callout on refcount=0.

With this in place, the rework can be done such that the node structure is
fully removed and deallocated when the remote port no longer exists and all
references are removed.  This removal logic, and the basic ref counting are
intrically tied, thus in a single patch.

Link: https://lore.kernel.org/r/20201115192646.12977-2-james.smart@broadcom.com
Co-developed-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 12 insertions, 16 deletions

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 0f0ab86cf192..d22ede4b9d74 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -3505,7 +3505,7 @@ lpfc_send_scsi_error_event(struct lpfc_hba *phba, struct lpfc_vport *vport,
 	struct lpfc_nodelist *pnode = lpfc_cmd->rdata->pnode;
 	unsigned long flags;
 
-	if (!pnode || !NLP_CHK_NODE_ACT(pnode))
+	if (!pnode)
 		return;
 
 	/* If there is queuefull or busy condition send a scsi event */
@@ -3925,7 +3925,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 			fast_path_evt->un.fabric_evt.subcategory =
 				(lpfc_cmd->status == IOSTAT_NPORT_BSY) ?
 				LPFC_EVENT_PORT_BUSY : LPFC_EVENT_FABRIC_BUSY;
-			if (pnode && NLP_CHK_NODE_ACT(pnode)) {
+			if (pnode) {
 				memcpy(&fast_path_evt->un.fabric_evt.wwpn,
 					&pnode->nlp_portname,
 					sizeof(struct lpfc_name));
@@ -3980,7 +3980,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 			}
 			if ((lpfc_cmd->status == IOSTAT_REMOTE_STOP)
 				&& (phba->sli_rev == LPFC_SLI_REV4)
-				&& (pnode && NLP_CHK_NODE_ACT(pnode))) {
+				&& pnode) {
 				/* This IO was aborted by the target, we don't
 				 * know the rxid and because we did not send the
 				 * ABTS we cannot generate and RRQ.
@@ -3995,8 +3995,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 			break;
 		}
 
-		if (!pnode || !NLP_CHK_NODE_ACT(pnode)
-		    || (pnode->nlp_state != NLP_STE_MAPPED_NODE))
+		if (!pnode || (pnode->nlp_state != NLP_STE_MAPPED_NODE))
 			cmd->result = DID_TRANSPORT_DISRUPTED << 16 |
 				      SAM_STAT_BUSY;
 	} else
@@ -4018,7 +4017,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 	   time_after(jiffies, lpfc_cmd->start_time +
 		msecs_to_jiffies(vport->cfg_max_scsicmpl_time))) {
 		spin_lock_irqsave(shost->host_lock, flags);
-		if (pnode && NLP_CHK_NODE_ACT(pnode)) {
+		if (pnode) {
 			if (pnode->cmd_qdepth >
 				atomic_read(&pnode->cmd_pending) &&
 				(atomic_read(&pnode->cmd_pending) >
@@ -4104,7 +4103,7 @@ lpfc_scsi_prep_cmnd(struct lpfc_vport *vport, struct lpfc_io_buf *lpfc_cmd,
 	bool sli4;
 	uint32_t fcpdl;
 
-	if (!pnode || !NLP_CHK_NODE_ACT(pnode))
+	if (!pnode)
 		return;
 
 	lpfc_cmd->fcp_rsp->rspSnsLen = 0;
@@ -4215,8 +4214,7 @@ lpfc_scsi_prep_task_mgmt_cmd(struct lpfc_vport *vport,
 	struct lpfc_rport_data *rdata = lpfc_cmd->rdata;
 	struct lpfc_nodelist *ndlp = rdata->pnode;
 
-	if (!ndlp || !NLP_CHK_NODE_ACT(ndlp) ||
-	    ndlp->nlp_state != NLP_STE_MAPPED_NODE)
+	if (!ndlp || ndlp->nlp_state != NLP_STE_MAPPED_NODE)
 		return 0;
 
 	piocbq = &(lpfc_cmd->cur_iocbq);
@@ -4551,7 +4549,7 @@ lpfc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *cmnd)
 	 * Catch race where our node has transitioned, but the
 	 * transport is still transitioning.
 	 */
-	if (!ndlp || !NLP_CHK_NODE_ACT(ndlp))
+	if (!ndlp)
 		goto out_tgt_busy;
 	if (lpfc_ndlp_check_qdepth(phba, ndlp)) {
 		if (atomic_read(&ndlp->cmd_pending) >= ndlp->cmd_qdepth) {
@@ -5050,7 +5048,7 @@ lpfc_send_taskmgmt(struct lpfc_vport *vport, struct scsi_cmnd *cmnd,
 	int status;
 
 	rdata = lpfc_rport_data_from_scsi_device(cmnd->device);
-	if (!rdata || !rdata->pnode || !NLP_CHK_NODE_ACT(rdata->pnode))
+	if (!rdata || !rdata->pnode)
 		return FAILED;
 	pnode = rdata->pnode;
 
@@ -5154,7 +5152,7 @@ lpfc_chk_tgt_mapped(struct lpfc_vport *vport, struct scsi_cmnd *cmnd)
 	 */
 	later = msecs_to_jiffies(2 * vport->cfg_devloss_tmo * 1000) + jiffies;
 	while (time_after(later, jiffies)) {
-		if (!pnode || !NLP_CHK_NODE_ACT(pnode))
+		if (!pnode)
 			return FAILED;
 		if (pnode->nlp_state == NLP_STE_MAPPED_NODE)
 			return SUCCESS;
@@ -5164,8 +5162,7 @@ lpfc_chk_tgt_mapped(struct lpfc_vport *vport, struct scsi_cmnd *cmnd)
 			return FAILED;
 		pnode = rdata->pnode;
 	}
-	if (!pnode || !NLP_CHK_NODE_ACT(pnode) ||
-	    (pnode->nlp_state != NLP_STE_MAPPED_NODE))
+	if (!pnode || (pnode->nlp_state != NLP_STE_MAPPED_NODE))
 		return FAILED;
 	return SUCCESS;
 }
@@ -5409,8 +5406,7 @@ lpfc_bus_reset_handler(struct scsi_cmnd *cmnd)
 		match = 0;
 		spin_lock_irq(shost->host_lock);
 		list_for_each_entry(ndlp, &vport->fc_nodes, nlp_listp) {
-			if (!NLP_CHK_NODE_ACT(ndlp))
-				continue;
+
 			if (vport->phba->cfg_fcp2_no_tgt_reset &&
 			    (ndlp->nlp_fcp_info & NLP_FCP_2_DEVICE))
 				continue;