On Thu, 2012-11-29 at 11:57 +0100, Krzysztof Mazur wrote:
> do we really need to wait here?
> Why don't just do something like that:
>
> tasklet_disable(&card->tlet);
> spin_lock(&card->tx_queue_lock);
> for each skb in queue
> SKB_CB(skb)->vcc = NULL;
> spin_unlock(&card->tx_queue_lock);
> tasklet_enable(&card->tlet);
>
> or if we really want to call vcc->pop() for such skbs:
>
> tasklet_disable(&card->tlet);
> spin_lock(&card->tx_queue_lock);
> for each skb in queue {
> skb_get(skb);
> solos_pop(SKB_CB(skb)->vcc, skb);
> SKB_CB(skb)->vcc = NULL;
> }
> spin_unlock(&card->tx_queue_lock);
> tasklet_enable(&card->tlet);Yes, we could certainly remove the packets from the tx_queue first. However, in the card->using_dma case there might be a skb for this vcc *currently* being DMA'd, and we'd still need to wait for that one. I suppose we could just have a waitqueue in *every* TX skb, and under card->tx_lock we could add ourselves to *that* waitqueue. Or just a global waitqueue for DMA tx_done, perhaps. But waiting for our own PKT_PCLOSE skb is just 'cleaner' in my view. It's simpler, and it's much easier to test. Even if I had DMA-capable hardware, I'd have to get the right timing to properly test that TX-pending-DMA case. So dequeuing the packets would only serve to make pclose() slightly faster, rather than simplifying it. It's hardly a fast path that we care about, and I've also already ensured that there should only be one or two packets queued per vcc *anyway*. So I'm mostly inclined not to bother. (I did fix the timeout argument to wait_for_completion_timeout()) -- dwmw2
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