Re: [patch 1/1] FC transport: Locking fix for common-code FC pass-through patch

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

I had tried to remind James that he needed this patch when he pulled in 
the pass-thru code.

Acked-by: James Smart <james.smart@emulex.com>

-- james s

Christof Schmitt wrote:
> From: Christof Schmitt <christof.schmitt@de.ibm.com>
>
> Fix this:
> ------------[ cut here ]------------
> Badness at block/blk-core.c:244
> CPU: 0 Tainted: G        W  2.6.31-rc1-00004-gd3a263a #3
> Process zfcp_wq (pid: 901, task: 000000002fb7a038, ksp: 000000002f02bc78)
> Krnl PSW : 0704300180000000 00000000002141ba (blk_remove_plug+0xb2/0xb8)
>            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3
> Krnl GPRS: 0000000000000001 0000000000000001 0000000022811440 0000000022811798
>            000000000027ff4e 0000000000000000 0000000000000000 000000002f00f000
>            070000000006a0f4 000000002af70000 000000002af2a800 00000000228d1c00
>            0000000022811440 000000000050c708 000000002f02bca8 000000002f02bc80
> Krnl Code: 00000000002141b0: b9140022		lgfr	%r2,%r2
>            00000000002141b4: 07fe		bcr	15,%r14
>            00000000002141b6: a7f40001		brc	15,2141b8
>           >00000000002141ba: a7f4ffbe		brc	15,214136
>            00000000002141be: 0707		bcr	0,%r7
>            00000000002141c0: ebaff0680024	stmg %r10,%r15,104(%r15)
>            00000000002141c6: c0d00017c2a9	larl	%r13,50c718
>            00000000002141cc: a7f13fc0		tmll	%r15,16320
> Call Trace:
> ([<000000000050e7d8>] C.272.16122+0x88/0x110)
>  [<00000000002141ec>] __blk_run_queue+0x2c/0x154
>  [<000000000028013a>] fc_remote_port_add+0x85e/0x95c
>  [<000000000037596e>] zfcp_scsi_rport_work+0xe6/0x148
>  [<000000000006908c>] worker_thread+0x25c/0x318
>  [<000000000006f10c>] kthread+0x94/0x9c
>  [<000000000001c2b2>] kernel_thread_starter+0x6/0xc
>  [<000000000001c2ac>] kernel_thread_starter+0x0/0xc
> INFO: lockdep is turned off.
> Last Breaking-Event-Address:
>  [<00000000002141b6>] blk_remove_plug+0xae/0xb8
>
> The FC pass-through support triggers the WARN_ON(!irqs_disabled()) in
> blk_plug_device. Since blk_plug_device requires being called with
> disabled interrupts, use spin_lock_irqsave in fc_bsg_goose_queue to
> disable the interrupts before calling into the block layer.
>
> Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
> ---
>
>  drivers/scsi/scsi_transport_fc.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff -urpN linux-2.6/drivers/scsi/scsi_transport_fc.c linux-2.6-patched/drivers/scsi/scsi_transport_fc.c
> --- linux-2.6/drivers/scsi/scsi_transport_fc.c	2009-06-26 09:56:55.000000000 +0200
> +++ linux-2.6-patched/drivers/scsi/scsi_transport_fc.c	2009-06-26 09:57:06.000000000 +0200
> @@ -3670,13 +3670,14 @@ 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)
> @@ -3684,7 +3685,7 @@ 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);
>  }
>
>
>