scsi: lpfc: Correct upcalling nvmet_fc transport during io done downcall

When the transport calls into the lpfc target to release an IO job
structure, which corresponds to an exchange, and if the driver was waiting
for an exchange in order to post a previously received command to the
transport, the driver immediately takes the IO job and reuses the context
for the prior command and calls nvmet_fc_rcv_fcp_req() to tell the
transport about a newly received command.

Problem is, the execution of the IO job release may be in the context of
the back end driver and its bio completion handlers, thus it may be in a
irq context and protection code kicks in in the bio and request layers that
are subsequently called.

Rework lpfc so that instead of immediately upcalling, queue it to a
deferred work thread and have the thread make the upcall.

Took advantage of this change to remove duplicated code with the normal
command receive path that preps the IO job and upcalls nvmet_fc. Created a
common routine both paths use.

Also corrected some errors that were found during review of the context
freeing and reuse - basically unlocked operations and a somewhat disjoint
set of calls to release associated job elements. Cleaned up this path and
added locks for coherency.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

3 files changed, 137 insertions, 112 deletions

diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h
index b710994a352e..ea97d82f99f9 100644
--- a/drivers/scsi/lpfc/lpfc.h
+++ b/drivers/scsi/lpfc/lpfc.h
@@ -144,6 +144,7 @@ struct lpfc_nvmet_ctxbuf {
 	struct lpfc_nvmet_rcv_ctx *context;
 	struct lpfc_iocbq *iocbq;
 	struct lpfc_sglq *sglq;
+	struct work_struct defer_work;
 };
 
 struct lpfc_dma_pool {
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index 0b27e8c5ae32..0d10dfc74018 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -73,6 +73,9 @@ static int lpfc_nvmet_unsol_ls_issue_abort(struct lpfc_hba *,
 					   uint32_t, uint16_t);
 static void lpfc_nvmet_wqfull_flush(struct lpfc_hba *, struct lpfc_queue *,
 				    struct lpfc_nvmet_rcv_ctx *);
+static void lpfc_nvmet_fcp_rqst_defer_work(struct work_struct *);
+
+static void lpfc_nvmet_process_rcv_fcp_req(struct lpfc_nvmet_ctxbuf *ctx_buf);
 
 static union lpfc_wqe128 lpfc_tsend_cmd_template;
 static union lpfc_wqe128 lpfc_treceive_cmd_template;
@@ -220,21 +223,19 @@ lpfc_nvmet_cmd_template(void)
 void
 lpfc_nvmet_defer_release(struct lpfc_hba *phba, struct lpfc_nvmet_rcv_ctx *ctxp)
 {
-	unsigned long iflag;
+	lockdep_assert_held(&ctxp->ctxlock);
 
 	lpfc_printf_log(phba, KERN_INFO, LOG_NVME_ABTS,
 			"6313 NVMET Defer ctx release xri x%x flg x%x\n",
 			ctxp->oxid, ctxp->flag);
 
-	spin_lock_irqsave(&phba->sli4_hba.abts_nvmet_buf_list_lock, iflag);
-	if (ctxp->flag & LPFC_NVMET_CTX_RLS) {
-		spin_unlock_irqrestore(&phba->sli4_hba.abts_nvmet_buf_list_lock,
-				       iflag);
+	if (ctxp->flag & LPFC_NVMET_CTX_RLS)
 		return;
-	}
+
 	ctxp->flag |= LPFC_NVMET_CTX_RLS;
+	spin_lock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
 	list_add_tail(&ctxp->list, &phba->sli4_hba.lpfc_abts_nvmet_ctx_list);
-	spin_unlock_irqrestore(&phba->sli4_hba.abts_nvmet_buf_list_lock, iflag);
+	spin_unlock(&phba->sli4_hba.abts_nvmet_buf_list_lock);
 }
 
 /**
@@ -325,7 +326,7 @@ lpfc_nvmet_ctxbuf_post(struct lpfc_hba *phba, struct lpfc_nvmet_ctxbuf *ctx_buf)
 	struct rqb_dmabuf *nvmebuf;
 	struct lpfc_nvmet_ctx_info *infop;
 	uint32_t *payload;
-	uint32_t size, oxid, sid, rc;
+	uint32_t size, oxid, sid;
 	int cpu;
 	unsigned long iflag;
 
@@ -341,6 +342,20 @@ lpfc_nvmet_ctxbuf_post(struct lpfc_hba *phba, struct lpfc_nvmet_ctxbuf *ctx_buf)
 				"6411 NVMET free, already free IO x%x: %d %d\n",
 				ctxp->oxid, ctxp->state, ctxp->entry_cnt);
 	}
+
+	if (ctxp->rqb_buffer) {
+		nvmebuf = ctxp->rqb_buffer;
+		spin_lock_irqsave(&ctxp->ctxlock, iflag);
+		ctxp->rqb_buffer = NULL;
+		if (ctxp->flag & LPFC_NVMET_CTX_REUSE_WQ) {
+			ctxp->flag &= ~LPFC_NVMET_CTX_REUSE_WQ;
+			spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
+			nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
+		} else {
+			spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
+			lpfc_rq_buf_free(phba, &nvmebuf->hbuf); /* repost */
+		}
+	}
 	ctxp->state = LPFC_NVMET_STE_FREE;
 
 	spin_lock_irqsave(&phba->sli4_hba.nvmet_io_wait_lock, iflag);
@@ -388,46 +403,30 @@ lpfc_nvmet_ctxbuf_post(struct lpfc_hba *phba, struct lpfc_nvmet_ctxbuf *ctx_buf)
 		}
 #endif
 		atomic_inc(&tgtp->rcv_fcp_cmd_in);
-		/*
-		 * The calling sequence should be:
-		 * nvmet_fc_rcv_fcp_req->lpfc_nvmet_xmt_fcp_op/cmp- req->done
-		 * lpfc_nvmet_xmt_fcp_op_cmp should free the allocated ctxp.
-		 * When we return from nvmet_fc_rcv_fcp_req, all relevant info
-		 * the NVME command / FC header is stored.
-		 * A buffer has already been reposted for this IO, so just free
-		 * the nvmebuf.
-		 */
-		rc = nvmet_fc_rcv_fcp_req(phba->targetport, &ctxp->ctx.fcp_req,
-					  payload, size);
 
-		/* Process FCP command */
-		if (rc == 0) {
-			ctxp->rqb_buffer = NULL;
-			atomic_inc(&tgtp->rcv_fcp_cmd_out);
-			nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
-			return;
-		}
+		/*  flag new work queued, replacement buffer has already
+		 *  been reposted
+		 */
+		spin_lock_irqsave(&ctxp->ctxlock, iflag);
+		ctxp->flag |= LPFC_NVMET_CTX_REUSE_WQ;
+		spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 
-		/* Processing of FCP command is deferred */
-		if (rc == -EOVERFLOW) {
-			lpfc_nvmeio_data(phba,
-					 "NVMET RCV BUSY: xri x%x sz %d "
-					 "from %06x\n",
-					 oxid, size, sid);
-			atomic_inc(&tgtp->rcv_fcp_cmd_out);
-			return;
+		if (!queue_work(phba->wq, &ctx_buf->defer_work)) {
+			atomic_inc(&tgtp->rcv_fcp_cmd_drop);
+			lpfc_printf_log(phba, KERN_ERR, LOG_NVME,
+					"6181 Unable to queue deferred work "
+					"for oxid x%x. "
+					"FCP Drop IO [x%x x%x x%x]\n",
+					ctxp->oxid,
+					atomic_read(&tgtp->rcv_fcp_cmd_in),
+					atomic_read(&tgtp->rcv_fcp_cmd_out),
+					atomic_read(&tgtp->xmt_fcp_release));
+
+			spin_lock_irqsave(&ctxp->ctxlock, iflag);
+			lpfc_nvmet_defer_release(phba, ctxp);
+			spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
+			lpfc_nvmet_unsol_fcp_issue_abort(phba, ctxp, sid, oxid);
 		}
-		atomic_inc(&tgtp->rcv_fcp_cmd_drop);
-		lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
-				"2582 FCP Drop IO x%x: err x%x: x%x x%x x%x\n",
-				ctxp->oxid, rc,
-				atomic_read(&tgtp->rcv_fcp_cmd_in),
-				atomic_read(&tgtp->rcv_fcp_cmd_out),
-				atomic_read(&tgtp->xmt_fcp_release));
-
-		lpfc_nvmet_defer_release(phba, ctxp);
-		lpfc_nvmet_unsol_fcp_issue_abort(phba, ctxp, sid, oxid);
-		nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
 		return;
 	}
 	spin_unlock_irqrestore(&phba->sli4_hba.nvmet_io_wait_lock, iflag);
@@ -1113,6 +1112,8 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 		container_of(rsp, struct lpfc_nvmet_rcv_ctx, ctx.fcp_req);
 	struct rqb_dmabuf *nvmebuf = ctxp->rqb_buffer;
 	struct lpfc_hba *phba = ctxp->phba;
+	unsigned long iflag;
+
 
 	lpfc_nvmeio_data(phba, "NVMET DEFERRCV: xri x%x sz %d CPU %02x\n",
 			 ctxp->oxid, ctxp->size, smp_processor_id());
@@ -1131,6 +1132,9 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 
 	/* Free the nvmebuf since a new buffer already replaced it */
 	nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
+	spin_lock_irqsave(&ctxp->ctxlock, iflag);
+	ctxp->rqb_buffer = NULL;
+	spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 }
 
 static struct nvmet_fc_target_template lpfc_tgttemplate = {
@@ -1323,6 +1327,7 @@ lpfc_nvmet_setup_io_context(struct lpfc_hba *phba)
 					"6407 Ran out of NVMET XRIs\n");
 			return -ENOMEM;
 		}
+		INIT_WORK(&ctx_buf->defer_work, lpfc_nvmet_fcp_rqst_defer_work);
 
 		/*
 		 * Add ctx to MRQidx context list. Our initial assumption
@@ -1824,6 +1829,86 @@ dropit:
 #endif
 }
 
+static void
+lpfc_nvmet_process_rcv_fcp_req(struct lpfc_nvmet_ctxbuf *ctx_buf)
+{
+#if (IS_ENABLED(CONFIG_NVME_TARGET_FC))
+	struct lpfc_nvmet_rcv_ctx *ctxp = ctx_buf->context;
+	struct lpfc_hba *phba = ctxp->phba;
+	struct rqb_dmabuf *nvmebuf = ctxp->rqb_buffer;
+	struct lpfc_nvmet_tgtport *tgtp;
+	uint32_t *payload;
+	uint32_t rc;
+	unsigned long iflags;
+
+	if (!nvmebuf) {
+		lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
+			"6159 process_rcv_fcp_req, nvmebuf is NULL, "
+			"oxid: x%x flg: x%x state: x%x\n",
+			ctxp->oxid, ctxp->flag, ctxp->state);
+		spin_lock_irqsave(&ctxp->ctxlock, iflags);
+		lpfc_nvmet_defer_release(phba, ctxp);
+		spin_unlock_irqrestore(&ctxp->ctxlock, iflags);
+		lpfc_nvmet_unsol_fcp_issue_abort(phba, ctxp, ctxp->sid,
+						 ctxp->oxid);
+		return;
+	}
+
+	payload = (uint32_t *)(nvmebuf->dbuf.virt);
+	tgtp = (struct lpfc_nvmet_tgtport *)phba->targetport->private;
+	/*
+	 * The calling sequence should be:
+	 * nvmet_fc_rcv_fcp_req->lpfc_nvmet_xmt_fcp_op/cmp- req->done
+	 * lpfc_nvmet_xmt_fcp_op_cmp should free the allocated ctxp.
+	 * When we return from nvmet_fc_rcv_fcp_req, all relevant info
+	 * the NVME command / FC header is stored.
+	 * A buffer has already been reposted for this IO, so just free
+	 * the nvmebuf.
+	 */
+	rc = nvmet_fc_rcv_fcp_req(phba->targetport, &ctxp->ctx.fcp_req,
+				  payload, ctxp->size);
+	/* Process FCP command */
+	if (rc == 0) {
+		atomic_inc(&tgtp->rcv_fcp_cmd_out);
+		return;
+	}
+
+	/* Processing of FCP command is deferred */
+	if (rc == -EOVERFLOW) {
+		lpfc_nvmeio_data(phba, "NVMET RCV BUSY: xri x%x sz %d "
+				 "from %06x\n",
+				 ctxp->oxid, ctxp->size, ctxp->sid);
+		atomic_inc(&tgtp->rcv_fcp_cmd_out);
+		atomic_inc(&tgtp->defer_fod);
+		return;
+	}
+	atomic_inc(&tgtp->rcv_fcp_cmd_drop);
+	lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
+			"2582 FCP Drop IO x%x: err x%x: x%x x%x x%x\n",
+			ctxp->oxid, rc,
+			atomic_read(&tgtp->rcv_fcp_cmd_in),
+			atomic_read(&tgtp->rcv_fcp_cmd_out),
+			atomic_read(&tgtp->xmt_fcp_release));
+	lpfc_nvmeio_data(phba, "NVMET FCP DROP: xri x%x sz %d from %06x\n",
+			 ctxp->oxid, ctxp->size, ctxp->sid);
+	spin_lock_irqsave(&ctxp->ctxlock, iflags);
+	lpfc_nvmet_defer_release(phba, ctxp);
+	spin_unlock_irqrestore(&ctxp->ctxlock, iflags);
+	lpfc_nvmet_unsol_fcp_issue_abort(phba, ctxp, ctxp->sid, ctxp->oxid);
+#endif
+}
+
+static void
+lpfc_nvmet_fcp_rqst_defer_work(struct work_struct *work)
+{
+#if (IS_ENABLED(CONFIG_NVME_TARGET_FC))
+	struct lpfc_nvmet_ctxbuf *ctx_buf =
+		container_of(work, struct lpfc_nvmet_ctxbuf, defer_work);
+
+	lpfc_nvmet_process_rcv_fcp_req(ctx_buf);
+#endif
+}
+
 static struct lpfc_nvmet_ctxbuf *
 lpfc_nvmet_replenish_context(struct lpfc_hba *phba,
 			     struct lpfc_nvmet_ctx_info *current_infop)
@@ -1906,7 +1991,7 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
 	struct lpfc_nvmet_ctxbuf *ctx_buf;
 	struct lpfc_nvmet_ctx_info *current_infop;
 	uint32_t *payload;
-	uint32_t size, oxid, sid, rc, qno;
+	uint32_t size, oxid, sid, qno;
 	unsigned long iflag;
 	int current_cpu;
 
@@ -1917,11 +2002,9 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
 	if (!nvmebuf || !phba->targetport) {
 		lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
 				"6157 NVMET FCP Drop IO\n");
-		oxid = 0;
-		size = 0;
-		sid = 0;
-		ctxp = NULL;
-		goto dropit;
+		if (nvmebuf)
+			lpfc_rq_buf_free(phba, &nvmebuf->hbuf);
+		return;
 	}
 
 	/*
@@ -2028,67 +2111,7 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
 #endif
 
 	atomic_inc(&tgtp->rcv_fcp_cmd_in);
-	/*
-	 * The calling sequence should be:
-	 * nvmet_fc_rcv_fcp_req -> lpfc_nvmet_xmt_fcp_op/cmp -> req->done
-	 * lpfc_nvmet_xmt_fcp_op_cmp should free the allocated ctxp.
-	 * When we return from nvmet_fc_rcv_fcp_req, all relevant info in
-	 * the NVME command / FC header is stored, so we are free to repost
-	 * the buffer.
-	 */
-	rc = nvmet_fc_rcv_fcp_req(phba->targetport, &ctxp->ctx.fcp_req,
-				  payload, size);
-
-	/* Process FCP command */
-	if (rc == 0) {
-		ctxp->rqb_buffer = NULL;
-		atomic_inc(&tgtp->rcv_fcp_cmd_out);
-		lpfc_rq_buf_free(phba, &nvmebuf->hbuf); /* repost */
-		return;
-	}
-
-	/* Processing of FCP command is deferred */
-	if (rc == -EOVERFLOW) {
-		/*
-		 * Post a brand new DMA buffer to RQ and defer
-		 * freeing rcv buffer till .defer_rcv callback
-		 */
-		qno = nvmebuf->idx;
-		lpfc_post_rq_buffer(
-			phba, phba->sli4_hba.nvmet_mrq_hdr[qno],
-			phba->sli4_hba.nvmet_mrq_data[qno], 1, qno);
-
-		lpfc_nvmeio_data(phba,
-				 "NVMET RCV BUSY: xri x%x sz %d from %06x\n",
-				 oxid, size, sid);
-		atomic_inc(&tgtp->rcv_fcp_cmd_out);
-		atomic_inc(&tgtp->defer_fod);
-		return;
-	}
-	ctxp->rqb_buffer = nvmebuf;
-
-	atomic_inc(&tgtp->rcv_fcp_cmd_drop);
-	lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
-			"6159 FCP Drop IO x%x: err x%x: x%x x%x x%x\n",
-			ctxp->oxid, rc,
-			atomic_read(&tgtp->rcv_fcp_cmd_in),
-			atomic_read(&tgtp->rcv_fcp_cmd_out),
-			atomic_read(&tgtp->xmt_fcp_release));
-dropit:
-	lpfc_nvmeio_data(phba, "NVMET FCP DROP: xri x%x sz %d from %06x\n",
-			 oxid, size, sid);
-	if (oxid) {
-		lpfc_nvmet_defer_release(phba, ctxp);
-		lpfc_nvmet_unsol_fcp_issue_abort(phba, ctxp, sid, oxid);
-		lpfc_rq_buf_free(phba, &nvmebuf->hbuf); /* repost */
-		return;
-	}
-
-	if (ctx_buf)
-		lpfc_nvmet_ctxbuf_post(phba, ctx_buf);
-
-	if (nvmebuf)
-		lpfc_rq_buf_free(phba, &nvmebuf->hbuf); /* repost */
+	lpfc_nvmet_process_rcv_fcp_req(ctx_buf);
 }
 
 /**
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.h b/drivers/scsi/lpfc/lpfc_nvmet.h
index 9b767c59de3d..b8c342a41d98 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.h
+++ b/drivers/scsi/lpfc/lpfc_nvmet.h
@@ -137,6 +137,7 @@ struct lpfc_nvmet_rcv_ctx {
 #define LPFC_NVMET_XBUSY		0x4  /* XB bit set on IO cmpl */
 #define LPFC_NVMET_CTX_RLS		0x8  /* ctx free requested */
 #define LPFC_NVMET_ABTS_RCV		0x10  /* ABTS received on exchange */
+#define LPFC_NVMET_CTX_REUSE_WQ		0x20  /* ctx reused via WQ */
 #define LPFC_NVMET_DEFER_WQFULL		0x40  /* Waiting on a free WQE */
 	struct rqb_dmabuf *rqb_buffer;
 	struct lpfc_nvmet_ctxbuf *ctxbuf;