[OpenPower-Firmware] [PATCH 2/2] scsi: lpfc: Limit xri count for kdump environment

[klaus at linux.vnet.ibm.com]

From: James Smart <jsmart2021 at gmail.com>

scsi-mq operation inherently performs pre-allocation of resources for
blk-mq request queues. Even though the kdump environment reduces the
configuration to a single CPU, thus 1 hardware queue, which helps
significantly, the resources are still rather large due to the per request
allocations. blk-mq pre-allocations can be over 4KB per request.  With
adapter can_queue values in the 4k or 8k range, this can easily be 32MBs
before any other driver memory is factored in.  Driver SGL DMA buffer
allocation can be up to 8KB per request as well adding an additional
64MB. Totals are well over 100MB for a single shost.  Given kdump memory
auto-sizing utilities don't accommodate this amount of memory well, it's
very possible for kdump to fail due to lack of memory.

Fix by having the driver recognize that it is booting within a kdump
context and reduce the number of requests it will support to a more
reasonable value.

Signed-off-by: Dick Kennedy <dick.kennedy at broadcom.com>
Signed-off-by: James Smart <jsmart2021 at gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
---
 drivers/scsi/lpfc/lpfc_init.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index a5b515fdda2e..7edbba7debc2 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -39,6 +39,7 @@
 #include <linux/msi.h>
 #include <linux/irq.h>
 #include <linux/bitops.h>
+#include <linux/crash_dump.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>
@@ -8309,6 +8310,10 @@ lpfc_sli4_read_config(struct lpfc_hba *phba)
 			bf_get(lpfc_mbx_rd_conf_extnts_inuse, rd_config);
 		phba->sli4_hba.max_cfg_param.max_xri =
 			bf_get(lpfc_mbx_rd_conf_xri_count, rd_config);
+		/* Reduce resource usage in kdump environment */
+		if (is_kdump_kernel() &&
+		    phba->sli4_hba.max_cfg_param.max_xri > 512)
+			phba->sli4_hba.max_cfg_param.max_xri = 512;
 		phba->sli4_hba.max_cfg_param.xri_base =
 			bf_get(lpfc_mbx_rd_conf_xri_base, rd_config);
 		phba->sli4_hba.max_cfg_param.max_vpi =
-- 
2.17.1