David,
Here is some comments on the 2.6.4 ohci driver relative to my original proposed patch:
- The state which I called ED_DESCHEDULED you represent with "ED_UNLINK && not on the ed_rm_list"
Actually I don't think there _is_ a state like that in the current driver ... although there's been one in the OHCI code ever since 2.2.early versions!
Stylistically, it's a bit strange for this state to be called ED_UNLINK (why would you have to call start_ed_unlink() when you're already in ED_UNLINK state?) but that's obviously a matter of taste more than anything else and has no functional effect.
Erm, not legal to call start_ed_unlink() when the state is already ED_UNLINK. It would hang otherwise, that's what made the rm_list (holding everything in ED_UNLINK) to loop back onto itself!!
- Your start_ed_unlink() doesn't disable the bulk/control list-scanning
like my patch did. Your version seems fine provided an ED never
transitions to ED_IDLE without the TD-queue first going empty
(in which case ed_deschedule() already takes care of
disabling the scanning of the appropriate list).
You haven't explained why that'd be a problem though. (I had pointed out a potential issue with -- rare -- schedules so busy that the control or bulk "current" entry never progressed, you didn't follow up on that.)
...
That's OK _provided_ the TD queue will eventually drain to empty. I think the only way this could be violated is if there were a continual stream of new submissions while someone is trying to do an ohci_endpoint_disable(). Not sure if that can happen.
Couldn't happen, the caller already blocked all new submissions.
In summary, the patches in 2.6.4 look very good to me. I'm quite certain it'll work at least as well (and probably better) than my proposed patch. I guess I would have appreciated if you had ack'd my contribution in tracking down some of the races, but I'm sure that was just an oversight.
You mean in patch comments, rather than in "thanks!" on the list? :) I was in a bit of a hurry.
- Dave
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