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, 1 insertions, 32 deletions

diff --git a/drivers/scsi/lpfc/lpfc_disc.h b/drivers/scsi/lpfc/lpfc_disc.h
index 1437e44ade80..f8ab001e4f0d 100644
--- a/drivers/scsi/lpfc/lpfc_disc.h
+++ b/drivers/scsi/lpfc/lpfc_disc.h
@@ -116,12 +116,6 @@ struct lpfc_nodelist {
 	u8		nlp_nvme_info;	        /* NVME NSLER Support */
 #define NLP_NVME_NSLER     0x1			/* NVME NSLER device */
 
-	uint16_t        nlp_usg_map;	/* ndlp management usage bitmap */
-#define NLP_USG_NODE_ACT_BIT	0x1	/* Indicate ndlp is actively used */
-#define NLP_USG_IACT_REQ_BIT	0x2	/* Request to inactivate ndlp */
-#define NLP_USG_FREE_REQ_BIT	0x4	/* Request to invoke ndlp memory free */
-#define NLP_USG_FREE_ACK_BIT	0x8	/* Indicate ndlp memory free invoked */
-
 	struct timer_list   nlp_delayfunc;	/* Used for delayed ELS cmds */
 	struct lpfc_hba *phba;
 	struct fc_rport *rport;		/* scsi_transport_fc port structure */
@@ -173,6 +167,7 @@ struct lpfc_node_rrq {
 #define NLP_FCP_PRLI_RJT   0x00002000   /* Rport does not support FCP PRLI. */
 #define NLP_UNREG_INP      0x00008000	/* UNREG_RPI cmd is in progress */
 #define NLP_DEFER_RM       0x00010000	/* Remove this ndlp if no longer used */
+#define NLP_DROPPED        0x00000008	/* Init ref count has been dropped */
 #define NLP_DELAY_TMO      0x00020000	/* delay timeout is running for node */
 #define NLP_NPR_2B_DISC    0x00040000	/* node is included in num_disc_nodes */
 #define NLP_RCV_PLOGI      0x00080000	/* Rcv'ed PLOGI from remote system */
@@ -191,32 +186,6 @@ struct lpfc_node_rrq {
 #define NLP_FIRSTBURST     0x40000000	/* Target supports FirstBurst */
 #define NLP_RPI_REGISTERED 0x80000000	/* nlp_rpi is valid */
 
-
-/* ndlp usage management macros */
-#define NLP_CHK_NODE_ACT(ndlp)		(((ndlp)->nlp_usg_map \
-						& NLP_USG_NODE_ACT_BIT) \
-					&& \
-					!((ndlp)->nlp_usg_map \
-						& NLP_USG_FREE_ACK_BIT))
-#define NLP_SET_NODE_ACT(ndlp)		((ndlp)->nlp_usg_map \
-						|= NLP_USG_NODE_ACT_BIT)
-#define NLP_INT_NODE_ACT(ndlp)		((ndlp)->nlp_usg_map \
-						= NLP_USG_NODE_ACT_BIT)
-#define NLP_CLR_NODE_ACT(ndlp)		((ndlp)->nlp_usg_map \
-						&= ~NLP_USG_NODE_ACT_BIT)
-#define NLP_CHK_IACT_REQ(ndlp)          ((ndlp)->nlp_usg_map \
-						& NLP_USG_IACT_REQ_BIT)
-#define NLP_SET_IACT_REQ(ndlp)          ((ndlp)->nlp_usg_map \
-						|= NLP_USG_IACT_REQ_BIT)
-#define NLP_CHK_FREE_REQ(ndlp)		((ndlp)->nlp_usg_map \
-						& NLP_USG_FREE_REQ_BIT)
-#define NLP_SET_FREE_REQ(ndlp)		((ndlp)->nlp_usg_map \
-						|= NLP_USG_FREE_REQ_BIT)
-#define NLP_CHK_FREE_ACK(ndlp)		((ndlp)->nlp_usg_map \
-						& NLP_USG_FREE_ACK_BIT)
-#define NLP_SET_FREE_ACK(ndlp)		((ndlp)->nlp_usg_map \
-						|= NLP_USG_FREE_ACK_BIT)
-
 /* There are 4 different double linked lists nodelist entries can reside on.
  * The Port Login (PLOGI) list and Address Discovery (ADISC) list are used
  * when Link Up discovery or Registered State Change Notification (RSCN)