Re: [PATCH] FC Pass Thru support

[James Smart <James.Smart@Emulex.Com>]

Thanks Christof.  I'll add it to the patch.

-- james s


Christof Schmitt wrote:
> 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);
>  }
>
>