RE: [PATCH 02/28] be2iscsi: Replace _bh with _irqsave/irqrestore

[Jitendra Bhivare]

> -----Original Message-----
> From: Martin K. Petersen [mailto:martin.peter...@oracle.com]
> Sent: Tuesday, August 09, 2016 6:35 AM
> To: Mike Christie
> Cc: Jitendra Bhivare; linux-scsi@vger.kernel.org
> Subject: Re: [PATCH 02/28] be2iscsi: Replace _bh with
_irqsave/irqrestore
>
> >>>>> "Mike" == Mike Christie <mchri...@redhat.com> writes:
>
> >> In beiscsi_alloc_pdu, _bh versions of spin_lock are being used for
> >> protecting SGLs and WRBs. _bh versions are needed as the function
> >> gets invoked in process context and BLOCK_IOPOLL softirq.
> >>
> >> In spin_unlock_bh, after releasing the lock and enabling BH,
> >> do_softirq is called which executes till last SOFTIRQ.
> >>
> >> beiscsi_alloc_pdu is called under session lock. Through block layer,
> >> iSCSI stack in some cases send IOs with interrupts disabled. In such
> >> paths,
>
>
> Mike> What path is this? Is this with mq enabled or disabled?
>
> Jitendra?
>
> --
> Martin K. Petersen    Oracle Linux Engineering
[JB] Sorry for the delayed response, there was some issue with my mail
client.
There are paths block layer where IRQs are disabled with request_queue
queue_lock.
- blk_timeout_work : this triggers NOP-OUT thru' iscsi_eh_cmd_timed_out.
- blk_execute_rq_nowait
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