Re: [PATCH] 2.5.15 IDE 62

Jens Axboe
2002-05-13T16:56:07Z

On Mon, May 13 2002, Linus Torvalds wrote:
> > Well on the channel level they are safe modulo cmd640 and rz1000.
> > We can handle them by serializing them on the global lock
> > in do_ide_request. Like:
> >
> > if (ch->drive[0].serialized|| ch->drive[1].serialized)
> > then
> > spin_lock(serialize_lock);
>
> NO.
>
> The whole point of having a per-queue lock pointer is that this should be
> initialized at queue creation time. Don't add more crud to the IDE
> locking, we want to get _rid_ of the locking that IDE has thought
> (traditionally incorrectly) that it could do better than the higher
> levels.
>
> So when you create the queue, you should decide at THAT point whether you
> just want to pass in the same lock or not.
>
> For a cmd640, you make sure that both queues get created with the same
> lock. And for non-broken chipsets, you use per-queue locks.
>
> And then you make sure that nobody EVER uses any other lock than the queue
> lock.

Completely agreed. And when we finally use the queue as the
serialization point for "everything", then it all falls into place
nicely.

--
Jens Axboe