Messages in this thread | | | Date | Thu, 13 Nov 2003 21:59:37 +1100 | From | Nick Piggin <> | Subject | Re: AS spin lock bugs |
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Jens Axboe wrote:
>On Thu, Nov 13 2003, Jens Axboe wrote: > >>@@ -959,12 +960,12 @@ >> if (!aic) >> return; >> >>- spin_lock(&aic->lock); >>+ spin_lock_irqsave(&aic->lock, flags); >> if (arq->is_sync == REQ_SYNC) { >> set_bit(AS_TASK_IORUNNING, &aic->state); >> aic->last_end_request = jiffies; >> } >>- spin_unlock(&aic->lock); >>+ spin_unlock_irqrestore(&aic->lock, flags); >> >> put_io_context(arq->io_context); >> } >> > >BTW, this looks bogus. Why do you need any locking there? >
To prevent a request completion on another queue on another CPU from racing with request insertion: last_end_request is undefined if the flag is not set. I guess you could flip the statements and put a smp_mb between them. Probably not worth the trouble though.
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