RE: [PATCH 20/29] ioat: switch watchdog and reset handler from workqueue to timer

Sosnowski, Maciej
2009-09-14T14:59:43Z

Williams, Dan J wrote:
> In order to support dynamic resizing of the descriptor ring or polling
> for a descriptor in the presence of a hung channel the reset handler
> needs to make progress while in a non-preemptible context. The current
> workqueue implementation precludes polling channel reset completion
> under spin_lock().
>
> This conversion also allows us to return to opportunistic cleanup in the
> ioat2 case as the timer implementation guarantees at least one cleanup
> after every descriptor is submitted. This means the worst case
> completion latency becomes the timer frequency (for exceptional
> circumstances), but with the benefit of avoiding busy waiting when the
> lock is contended.
>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---

[...]
> --- a/drivers/dma/ioat/dma_v2.c
> +++ b/drivers/dma/ioat/dma_v2.c
> @@ -49,7 +49,7 @@ static void __ioat2_issue_pending(struct ioat2_dma_chan *ioat)
> void * __iomem reg_base = ioat->base.reg_base;
>
> ioat->pending = 0;
> - ioat->dmacount += ioat2_ring_pending(ioat);
> + ioat->dmacount += ioat2_ring_pending(ioat);;
double semicolon