On Wed, 2016-04-27 at 12:39 +0200, Hannes Reinecke wrote: > On 04/27/2016 10:48 AM, Johannes Thumshirn wrote: > > The qla1280 driver sets the scsi_host_template's can_queue field to > > 0xfffff > > which results in an allocation failure when allocating the block > > layer tags > > for the driver's queues. This was introduced with the change for > > host wide > > tags in commit 64d513ac31b - "scsi: use host wide tags by default". > > > > Reduce can_queue to MAX_OUTSTANDING_COMMANDS (512) to solve the > > allocation > > error. > > > > Signed-off-by: Johannes Thumshirn <[email protected]> > > Fixes: 64d513ac31b - "scsi: use host wide tags by default" > > Cc: [email protected] # v4.4 > > Cc: Laura Abbott <[email protected]> > > Cc: Michael Reed <[email protected]> > > Reviewed-by: Laurence Oberman <[email protected]> > > Reviewed-by: Lee Duncan <[email protected]> > > --- > > Changes to v4: > > * Make subject more meaningfull > > * Remove warning's backtrace > > * Re-add reference to commit 64d513ac31b - "scsi: use host wide > > tags by default" > > > > Changes to v3: > > * Use MAX_OUTSTANDING_COMMANDS insted of hard coded magical number > > > > Changes to v2: > > * Change can_queue to 512 upon James' request > > > > drivers/scsi/qla1280.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/scsi/qla1280.c b/drivers/scsi/qla1280.c > > index 5d0ec42..634254a 100644 > > --- a/drivers/scsi/qla1280.c > > +++ b/drivers/scsi/qla1280.c > > @@ -4214,7 +4214,7 @@ static struct scsi_host_template > > qla1280_driver_template = { > > .eh_bus_reset_handler = qla1280_eh_bus_reset, > > .eh_host_reset_handler = qla1280_eh_adapter_reset, > > .bios_param = qla1280_biosparam, > > - .can_queue = 0xfffff, > > + .can_queue = MAX_OUTSTANDING_COMMANDS, > > .this_id = -1, > > .sg_tablesize = SG_ALL, > > .use_clustering = ENABLE_CLUSTERING, > > > Hmm. > > The driver has this: > > ha->request_ring = pci_alloc_consistent(ha->pdev, > ((REQUEST_ENTRY_CNT + 1) * sizeof(request_t)), > &ha->request_dma); > > and > > /* ISP request and response entry counts (37-65535) */ > #define REQUEST_ENTRY_CNT 255 /* Number of request entries. */ > #define RESPONSE_ENTRY_CNT 63 /* Number of response entries. > */ > > IE the driver (as it stands currently) will never be able to queue > more than 255 requests. > So where's the point in setting can_queue to 512? Shouldn't we > rather use 255 here?
Because that's for the request/response message ring. You don't keep a request allocated while the command is outstanding, you send a request message with the command handle (the index into the outstanding_cmds array) and a pointer to the command and get a response back when the firmware accepts it (at which time you can re-use the request). You eventually get a completion interrupt with MBA_SCSI_COMPLETION and a handle number (index into the outstanding_cmds array) when the host is done with the command. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
