mpt2sas, mpt3sas: fix upper bound for the module parameter max_sgl_entries

Change Set:

1. Extended the upper boundary restriction for the module parameter
   max_sgl_entries. Earlier, the max_sgl_entries was capped at the
   SCSI_MAX_SG_SEGMENTS kernel definition. With this change, the user
   would be able to set the max_sgl_entries to any value which is
   greater than SCSI_MAX_SG_SEGMENTS and less than the minimum of
   SCSI_MAX_SG_CHAIN_SEGMENTS & hardware limit (Calculated using
   IOCFacts's MaxChainDepth).

2. Added a print for the message log whenever the user sets the
   max_sgl_entries to a value greater than SCSI_MAX_SG_SEGMENTS to
   warn about the kernel definition overriding.

Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

2 files changed, 15 insertions, 5 deletions

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
index 14ebb54fae33..88c80efa7d7b 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -2492,9 +2492,13 @@ _base_allocate_memory_pools(struct MPT2SAS_ADAPTER *ioc,  int sleep_flag)
 
         /* command line tunables  for max sgl entries */
         if (max_sgl_entries != -1) {
-                ioc->shost->sg_tablesize = (max_sgl_entries <
-                    MPT2SAS_SG_DEPTH) ? max_sgl_entries :
-                    MPT2SAS_SG_DEPTH;
+                ioc->shost->sg_tablesize =  min_t(unsigned short,
+                             max_sgl_entries, SCSI_MAX_SG_CHAIN_SEGMENTS);
+                if (ioc->shost->sg_tablesize > MPT2SAS_SG_DEPTH)
+                        printk(MPT2SAS_WARN_FMT
+                         "sg_tablesize(%u) is bigger than kernel defined"
+                         " SCSI_MAX_SG_SEGMENTS(%u)\n", ioc->name,
+                          ioc->shost->sg_tablesize, MPT2SAS_SG_DEPTH);
         } else {
                 ioc->shost->sg_tablesize = MPT2SAS_SG_DEPTH;
         }
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 678e1ff33f1e..a428fdd43df5 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -2666,8 +2666,14 @@ _base_allocate_memory_pools(struct MPT3SAS_ADAPTER *ioc,  int sleep_flag)
 
         if (sg_tablesize < MPT3SAS_MIN_PHYS_SEGMENTS)
                 sg_tablesize = MPT3SAS_MIN_PHYS_SEGMENTS;
-        else if (sg_tablesize > MPT3SAS_MAX_PHYS_SEGMENTS)
-                sg_tablesize = MPT3SAS_MAX_PHYS_SEGMENTS;
+        else if (sg_tablesize > MPT3SAS_MAX_PHYS_SEGMENTS) {
+                sg_tablesize = min_t(unsigned short, sg_tablesize,
+                                      SCSI_MAX_SG_CHAIN_SEGMENTS);
+                pr_warn(MPT3SAS_FMT
+                 "sg_tablesize(%u) is bigger than kernel"
+                 " defined SCSI_MAX_SG_SEGMENTS(%u)\n", ioc->name,
+                 sg_tablesize, MPT3SAS_MAX_PHYS_SEGMENTS);
+        }
         ioc->shost->sg_tablesize = sg_tablesize;
 
         ioc->hi_priority_depth = facts->HighPriorityCredit;