linux-kernel - Re: [PATCH] dmaengine: dmatest: timeout value of -1 should specify infinite wait

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Message-ID: <20190604122356.GY15118@vkoul-mobl>
Date:   Tue, 4 Jun 2019 17:53:56 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     "Hook, Gary" <Gary.Hook@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dmaengine: dmatest: timeout value of -1 should specify
 infinite wait

On 31-05-19, 19:43, Hook, Gary wrote:
> The dmatest module parameter 'timeout' is documented as accepting a
> -1 to mean "infinite timeout". Change the parameter to to signed
> integer, and check the value to call the appropriate wait_event()
> function.
> 
> Signed-off-by: Gary R Hook <gary.hook@....com>
> ---
>  drivers/dma/dmatest.c |   11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
> index b96814a7dceb..28a237686578 100644
> --- a/drivers/dma/dmatest.c
> +++ b/drivers/dma/dmatest.c
> @@ -63,7 +63,7 @@ MODULE_PARM_DESC(pq_sources,
>  		"Number of p+q source buffers (default: 3)");
>  
>  static int timeout = 3000;
> -module_param(timeout, uint, S_IRUGO | S_IWUSR);
> +module_param(timeout, int, S_IRUGO | S_IWUSR);
>  MODULE_PARM_DESC(timeout, "Transfer Timeout in msec (default: 3000), "
>  		 "Pass -1 for infinite timeout");
>  
> @@ -795,8 +795,13 @@ static int dmatest_func(void *data)
>  		}
>  		dma_async_issue_pending(chan);
>  
> -		wait_event_freezable_timeout(thread->done_wait, done->done,
> -					     msecs_to_jiffies(params->timeout));
> +		/* A timeout value of -1 means infinite wait */
> +		if (timeout == -1)
> +			wait_event_freezable(thread->done_wait, done->done);

well i am not too happy that we have a infinite wait and no way to
cancel, maybe remove this case?

> +		else
> +			wait_event_freezable_timeout(thread->done_wait,
> +					done->done,
> +					msecs_to_jiffies(params->timeout));
>  
>  		status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
>  
> 

-- 
~Vinod