[SCSI] mpt2sas: Fix for Driver oops, when loading driver with max_queue_depth command line option to a very small value

If the specified max_queue_depth setting is less than the
expected number of internal commands, then driver will calculate
the queue depth size to a negitive number. This negitive number
is actually a very large number because variable is unsigned
16bit integer. So, the driver will ask for a very large amount of
memory for message frames and resulting into oops as memory
allocation routines will not able to handle such a large request.

So, in order to limit this kind of oops, The driver need to set
the max_queue_depth to a scsi mid layer's can_queue value. Then
the overall message frames required for IO is minimum of either
(max_queue_depth plus internal commands) or the IOC global
credits.

Signed-off-by: Sreekanth Reddy <sreekanth.reddy@lsi.com>
Cc: <stable@kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
index 9d46fcbe7755..b25757d1e91b 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -2424,10 +2424,13 @@ _base_allocate_memory_pools(struct MPT2SAS_ADAPTER *ioc,  int sleep_flag)
         }
 
         /* command line tunables  for max controller queue depth */
-        if (max_queue_depth != -1)
-                max_request_credit = (max_queue_depth < facts->RequestCredit)
-                    ? max_queue_depth : facts->RequestCredit;
-        else
+        if (max_queue_depth != -1 && max_queue_depth != 0) {
+                max_request_credit = min_t(u16, max_queue_depth +
+                        ioc->hi_priority_depth + ioc->internal_depth,
+                        facts->RequestCredit);
+                if (max_request_credit > MAX_HBA_QUEUE_DEPTH)
+                        max_request_credit =  MAX_HBA_QUEUE_DEPTH;
+        } else
                 max_request_credit = min_t(u16, facts->RequestCredit,
                     MAX_HBA_QUEUE_DEPTH);
 
@@ -2502,7 +2505,7 @@ _base_allocate_memory_pools(struct MPT2SAS_ADAPTER *ioc,  int sleep_flag)
         /* set the scsi host can_queue depth
          * with some internal commands that could be outstanding
          */
-        ioc->shost->can_queue = ioc->scsiio_depth - (2);
+        ioc->shost->can_queue = ioc->scsiio_depth;
         dinitprintk(ioc, printk(MPT2SAS_INFO_FMT "scsi host: "
             "can_queue depth (%d)\n", ioc->name, ioc->shost->can_queue));