Re: [PATCH] FC Pass Thru support

Christof Schmitt
2009-04-15T12:59:59Z

On Thu, Mar 26, 2009 at 01:33:19PM -0400, James Smart wrote:
>
> All,
>
> Attached is the ELS/CT pass-thru patch for the FC Transport. The patch
> creates a generic framework that lays on top of bsg and the SGIO v4 ioctl
> in order to pass transaction requests to LLDD's.
>
> The interface supports the following operations:
> On an fc_host basis:
> Request login to the specified N_Port_ID, creating an fc_rport.
> Request logout of the specified N_Port_ID, deleting an fc_rport
> Send ELS request to specified N_Port_ID w/o requiring a login, and
> wait for ELS response.
> Send CT request to specified N_Port_ID and wait for CT response.
> Login is required, but LLDD is allowed to manage login and decide
> whether it stays in place after the request is satisfied.
> Vendor-Unique request. Allows a LLDD-specific request to be passed
> to the LLDD, and the passing of a response back to the application.
> On an fc_rport basis:
> Send ELS request to nport and wait for ELS response.
> Send CT request to nport and wait for CT response.
>
> The patch also exports several headers from include/scsi such that
> they can be available to user-space applications:
> include/scsi/scsi.h
> include/scsi/scsi_netlink.h
> include/scsi/scsi_netlink_fc.h
> include/scsi/scsi_bsg_fc.h
>
> For further information, refer to the last RFC:
> http://marc.info/?l=linux-scsi&m=123436574018579&w=2

This patch triggers the warning WARN_ON(!irqs_disabled()) in
blk_remove_plug, and the description of __blk_run_queue states:

/**
* __blk_run_queue - run a single device queue
* @q: The queue to run
*
* Description:
* See @blk_run_queue. This variant must be called with the queue
* lock held and interrupts disabled.
*
*/

I assume to get this right, fc_bsg_goose_queue should disable
interrupts when taking the queue lock. See patch below.

Christof
---
drivers/scsi/scsi_transport_fc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/scsi/scsi_transport_fc.c 2009-04-14 14:29:25.000000000 +0200
+++ b/drivers/scsi/scsi_transport_fc.c 2009-04-14 14:31:41.000000000 +0200
@@ -3707,13 +3707,14 @@ static void
fc_bsg_goose_queue(struct fc_rport *rport)
{
int flagset;
+ unsigned long flags;

if (!rport->rqst_q)
return;

get_device(&rport->dev);

- spin_lock(rport->rqst_q->queue_lock);
+ spin_lock_irqsave(rport->rqst_q->queue_lock, flags);
flagset = test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags) &&
!test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags);
if (flagset)
@@ -3721,7 +3722,7 @@ fc_bsg_goose_queue(struct fc_rport *rpor
__blk_run_queue(rport->rqst_q);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q);
- spin_unlock(rport->rqst_q->queue_lock);
+ spin_unlock_irqrestore(rport->rqst_q->queue_lock, flags);

put_device(&rport->dev);
}