Re: [PATCH 3/3] dma: cppi41: move -EAGAIN in tear_down

[Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>]

* Daniel Mack | 2013-10-01 15:31:11 [+0200]:

>In cppi41_tear_down_chan(), bail out earlier in case td_seen is unset
>instead of popping another descriptor when td_desc_seen is also unset.
>
>My system ran into WARN() condition multiple times when
>cppi41_tear_down_chan() was called for channels that had all of
>td_queued, td_seen and td_seen set to false.

Which one?

>Signed-off-by: Daniel Mack <zonque-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>---
> drivers/dma/cppi41.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
>index 7747bf7..6decf34 100644
>--- a/drivers/dma/cppi41.c
>+++ b/drivers/dma/cppi41.c
>@@ -586,6 +586,9 @@ static int cppi41_tear_down_chan(struct cppi41_channel *c)
> 			}
> 			c->td_seen = 1;
> 		}
>+
>+		if (c->td_retry)
>+			return -EAGAIN;

So you return right away since the retry counter should be > 0 here. And
then you want to get the TDDOWN bit set and retry. Hmmm.
Let me answer to you 0/3 on this.

> 	}
> 	if (!c->td_desc_seen) {
> 		desc_phys = cppi41_pop_desc(cdd, c->q_comp_num);
>@@ -606,8 +609,6 @@ static int cppi41_tear_down_chan(struct cppi41_channel *c)
> 	 * descriptor before the TD we fetch it from enqueue, it has to be
> 	 * there waiting for us.
> 	 */
>-	if (!c->td_seen && c->td_retry)
>-		return -EAGAIN;
> 
> 	WARN_ON(!c->td_retry);
> 	if (!c->td_desc_seen) {

Sebastian
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