Messages in this thread | | | Date | Thu, 13 Nov 2003 21:52:22 +1100 | From | Nick Piggin <> | Subject | Re: AS spin lock bugs |
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Jens Axboe wrote:
>Hi, > >Was looking at io tracking for cfq, and I think I found some spin lock >bugs in current as (current BK). as_update_iohist() runs from >add_request which is typically in process context. It could be run with >interrupts disabled though, either driver private stuff or using the >generic block layer tagging. > >Anyways, as_update_iohist() grabs aic->lock without disabling >interrupts, while as_completed_request() typically runs at interrupt >time and grabs the same lock. Deadlock. > >To be safe, both need to use the flags saving lock variants. >
Hi Jens, I was hoping everything ran under the queue lock which should always have interrupts off on the local CPU. The lock in question is to prevent a as_completed_request on one queue from racing with as_update_iohist on another. Each would be on a different CPU.
Maybe I'm wrong, did you actually see misbehaviour?
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