scsi: lpfc: Fix random heartbeat timeouts during heavy IO

NVME targets appear to randomly disconnect from the initiator when
running heavy IO.

The error is due to the host aggregate (across all controllers) io load
was beyond the maximum exchange count for nvme on the adapter. The
driver was properly returning a resource busy status, but the io load
was so great heartbeat commands would be bounced and not have a
successful retry within the fuzz amount for the nvme heartbeat (yes, a
very high io load!). Thus the target was terminating the controller due
to a keep alive failure.

Resolve by reserving a few exchanges (by counters) which can be used
when the adapter is out of normal exchanges and the command is a NVME
heartbeat command. As counters are used, while the reserved command is
outstanding, as soon as any other exchange completes, the counters are
adjusted and the reserved count is replenished. The heartbeat completes
execution in a normal fashion.

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

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index fa211550a32a..44a98bc913f5 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -1034,6 +1034,7 @@ lpfc_hba_down_post_s4(struct lpfc_hba *phba)
 	LIST_HEAD(nvmet_aborts);
 	unsigned long iflag = 0;
 	struct lpfc_sglq *sglq_entry = NULL;
+	int cnt;
 
 
 	lpfc_sli_hbqbuf_free_all(phba);
@@ -1090,11 +1091,14 @@ lpfc_hba_down_post_s4(struct lpfc_hba *phba)
 	spin_unlock_irqrestore(&phba->scsi_buf_list_put_lock, iflag);
 
 	if (phba->cfg_enable_fc4_type & LPFC_ENABLE_NVME) {
+		cnt = 0;
 		list_for_each_entry_safe(psb, psb_next, &nvme_aborts, list) {
 			psb->pCmd = NULL;
 			psb->status = IOSTAT_SUCCESS;
+			cnt++;
 		}
 		spin_lock_irqsave(&phba->nvme_buf_list_put_lock, iflag);
+		phba->put_nvme_bufs += cnt;
 		list_splice(&nvme_aborts, &phba->lpfc_nvme_buf_list_put);
 		spin_unlock_irqrestore(&phba->nvme_buf_list_put_lock, iflag);
 
@@ -3339,6 +3343,7 @@ lpfc_nvme_free(struct lpfc_hba *phba)
 	list_for_each_entry_safe(lpfc_ncmd, lpfc_ncmd_next,
 				 &phba->lpfc_nvme_buf_list_put, list) {
 		list_del(&lpfc_ncmd->list);
+		phba->put_nvme_bufs--;
 		dma_pool_free(phba->lpfc_sg_dma_buf_pool, lpfc_ncmd->data,
 			      lpfc_ncmd->dma_handle);
 		kfree(lpfc_ncmd);
@@ -3350,6 +3355,7 @@ lpfc_nvme_free(struct lpfc_hba *phba)
 	list_for_each_entry_safe(lpfc_ncmd, lpfc_ncmd_next,
 				 &phba->lpfc_nvme_buf_list_get, list) {
 		list_del(&lpfc_ncmd->list);
+		phba->get_nvme_bufs--;
 		dma_pool_free(phba->lpfc_sg_dma_buf_pool, lpfc_ncmd->data,
 			      lpfc_ncmd->dma_handle);
 		kfree(lpfc_ncmd);
@@ -3754,9 +3760,11 @@ lpfc_sli4_nvme_sgl_update(struct lpfc_hba *phba)
 	uint16_t i, lxri, els_xri_cnt;
 	uint16_t nvme_xri_cnt, nvme_xri_max;
 	LIST_HEAD(nvme_sgl_list);
-	int rc;
+	int rc, cnt;
 
 	phba->total_nvme_bufs = 0;
+	phba->get_nvme_bufs = 0;
+	phba->put_nvme_bufs = 0;
 
 	if (!(phba->cfg_enable_fc4_type & LPFC_ENABLE_NVME))
 		return 0;
@@ -3780,6 +3788,9 @@ lpfc_sli4_nvme_sgl_update(struct lpfc_hba *phba)
 	spin_lock(&phba->nvme_buf_list_put_lock);
 	list_splice_init(&phba->lpfc_nvme_buf_list_get, &nvme_sgl_list);
 	list_splice(&phba->lpfc_nvme_buf_list_put, &nvme_sgl_list);
+	cnt = phba->get_nvme_bufs + phba->put_nvme_bufs;
+	phba->get_nvme_bufs = 0;
+	phba->put_nvme_bufs = 0;
 	spin_unlock(&phba->nvme_buf_list_put_lock);
 	spin_unlock_irq(&phba->nvme_buf_list_get_lock);
 
@@ -3824,6 +3835,7 @@ lpfc_sli4_nvme_sgl_update(struct lpfc_hba *phba)
 	spin_lock_irq(&phba->nvme_buf_list_get_lock);
 	spin_lock(&phba->nvme_buf_list_put_lock);
 	list_splice_init(&nvme_sgl_list, &phba->lpfc_nvme_buf_list_get);
+	phba->get_nvme_bufs = cnt;
 	INIT_LIST_HEAD(&phba->lpfc_nvme_buf_list_put);
 	spin_unlock(&phba->nvme_buf_list_put_lock);
 	spin_unlock_irq(&phba->nvme_buf_list_get_lock);
@@ -5609,8 +5621,10 @@ lpfc_setup_driver_resource_phase1(struct lpfc_hba *phba)
 		/* Initialize the NVME buffer list used by driver for NVME IO */
 		spin_lock_init(&phba->nvme_buf_list_get_lock);
 		INIT_LIST_HEAD(&phba->lpfc_nvme_buf_list_get);
+		phba->get_nvme_bufs = 0;
 		spin_lock_init(&phba->nvme_buf_list_put_lock);
 		INIT_LIST_HEAD(&phba->lpfc_nvme_buf_list_put);
+		phba->put_nvme_bufs = 0;
 	}
 
 	/* Initialize the fabric iocb list */