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SubjectRe: [PATCH 1/2] Convert target drivers to use sbitmap
On Tue, Jun 12, 2018 at 04:32:03PM +0000, Bart Van Assche wrote:
> On Tue, 2018-06-12 at 09:15 -0700, Matthew Wilcox wrote:
> > On Tue, Jun 12, 2018 at 03:22:42PM +0000, Bart Van Assche wrote:
> > > Please introduce functions in the target core for allocating and freeing a tag
> > > instead of spreading the knowledge of how to allocate and free tags over all
> > > target drivers.
> >
> > I can't without doing an unreasonably large amount of work on drivers that
> > I have no way to test. Some of the drivers have the se_cmd already; some
> > of them don't. I'd be happy to introduce a common function for freeing
> > a tag.
> Which target drivers are you referring to? If you are referring to the sbp driver:
> I think that driver is dead and can be removed from the kernel tree. I even don't
> know whether that driver ever has had any users other than the developer of that
> driver.

For example tcm_fc:

tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
if (tag < 0)
goto busy;

cmd = &((struct ft_cmd *)se_sess->sess_cmd_map)[tag];

or qla2xxx:

tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
if (tag < 0)
return NULL;

cmd = &((struct qla_tgt_cmd *)se_sess->sess_cmd_map)[tag];

The core doesn't know at what offset from the pointer to store the tag
& cpu. Only the individual drivers know their cmd layout.

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