Re: [RFC] Remove of ISA pools, and Lazy sense allocation.

[FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>]

On Wed, 07 May 2008 13:57:40 +0300
Boaz Harrosh <bharrosh@panasas.com> wrote:

> Let me please explain a bit on my sense_buffer patchset and where I was going 
> with these:
> 
> Currently every ULD/Initiator that pushes request to block devices puts a sense
> buffer of SCSI_SENSE_BUFFERSIZE size onto request->sense pointer. scsi-midlayer
> shadows that buffer, for what it thought as a DMAable buffer for drivers, and at
> completion of request copies the shadow buffer back into ULD's buffer.
> 
> I have observed three uses of sense_buffer handling in scsi drivers:

I just had a quick look at only some of patches, but where do you
allocate rq->sense for fs requests?


Here are some comments:

scsi_eh: Define API for driver private sense allocation

+struct scsi_sense_elem {
+       union {
+               struct scsi_sense_elem *next;
+               u8 sense_data[SCSI_SENSE_BUFFERSIZE] ____cacheline_aligned;
+       };
+} ____cacheline_aligned;


I think that this is wrong since all the architecutures don't have
such dma restriction. ARCH_KMALLOC_MINALIGN?

There is the same code in The libata patch at least. I guess there are
more.