> Shouldn't you be capping at SCSI_MAX_SG_CHAIN_SEGMENTS (or the actual hw
> limit)?

Agreed. And set the Upper limit to SCSI_MAX_SG_CHAIN_SEGMENTS.

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.re...@avagotech.com>
---
 drivers/scsi/mpt2sas/mpt2sas_base.c | 10 +++++++---
 drivers/scsi/mpt3sas/mpt3sas_base.c | 10 ++++++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c 
b/drivers/scsi/mpt2sas/mpt2sas_base.c
index 58e4521..ca3b564 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -2486,9 +2486,13 @@ _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;
+               if (max_sgl_entries > MPT2SAS_SG_DEPTH)
+                       printk(MPT2SAS_WARN_FMT
+                        "setting max_sgl_entries(%d), overriding kernel"
+                        " defined SCSI_MAX_SG_SEGMENTS(%d)\n", ioc->name,
+                         max_sgl_entries, MPT2SAS_SG_DEPTH);
+               ioc->shost->sg_tablesize =  min_t(unsigned short,
+                            max_sgl_entries, SCSI_MAX_SG_CHAIN_SEGMENTS);
        } 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 1560115..96db582 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -2659,8 +2659,14 @@ _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) {
+               pr_warn(MPT3SAS_FMT
+                "setting max_sgl_entries(%d), overriding kernel"
+                " defined SCSI_MAX_SG_SEGMENTS(%d)\n", ioc->name,
+                max_sgl_entries, MPT3SAS_MAX_PHYS_SEGMENTS);
+               sg_tablesize = min_t(unsigned short, sg_tablesize,
+                                     SCSI_MAX_SG_CHAIN_SEGMENTS);
+       }
        ioc->shost->sg_tablesize = sg_tablesize;
 
        ioc->hi_priority_depth = facts->HighPriorityCredit;
-- 
2.0.2

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