[ 088/108] SCSI: mpt2sas: Fix for Driver oops, when loading driver with max_queue_depth command line option to a very small value

From: Greg Kroah-Hartman
Date: Wed Sep 12 2012 - 20:21:38 EST

From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.5-stable review patch. If anyone has any objections, please let me know.


From: "sreekanth.reddy@xxxxxxx" <sreekanth.reddy@xxxxxxx>

commit 338b131a3269881c7431234855c93c219b0979b6 upstream.

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

Signed-off-by: Sreekanth Reddy <sreekanth.reddy@xxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/scsi/mpt2sas/mpt2sas_base.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -2424,10 +2424,13 @@ _base_allocate_memory_pools(struct MPT2S

/* 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,

@@ -2502,7 +2505,7 @@ _base_allocate_memory_pools(struct MPT2S
/* 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));

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