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

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

[Hook, Gary]

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@amd.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);
+		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);
 

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

[Vinod Koul]

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@amd.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

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

[Gary R Hook]

On 6/4/19 7:23 AM, Vinod Koul wrote:
> [CAUTION: External Email]
> 
> 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@amd.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?

Well, I was uncomfortable with documentation that didn't match behavior.

I see two choices (and I just chose one to start a conversation):

1) Accept this patch, with an infinite timeout, or
2) Leave the data type alone, but change the description to state that 
timeout values up to hex 0xFFFFFFFF / decimal 4294967295 can be used, 
emulating an "infinite" wait. A very long wait that eventually pops a 
timer is probably preferable. I don't think there are any conversion 
issues since the jiffy parameter to wait_event_freezable_timeout() is 
converted to a long. I could be wrong about that.

I'm happy to go with option (2). Please suggest a course of action.

grh

> 
>> +             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);

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

[Vinod Koul]

On 04-06-19, 16:47, Gary R Hook wrote:

> Well, I was uncomfortable with documentation that didn't match behavior.

That is the right way :)
> 
> I see two choices (and I just chose one to start a conversation):
> 
> 1) Accept this patch, with an infinite timeout, or
> 2) Leave the data type alone, but change the description to state that 
> timeout values up to hex 0xFFFFFFFF / decimal 4294967295 can be used, 
> emulating an "infinite" wait. A very long wait that eventually pops a 
> timer is probably preferable. I don't think there are any conversion 
> issues since the jiffy parameter to wait_event_freezable_timeout() is 
> converted to a long. I could be wrong about that.
> 
> I'm happy to go with option (2). Please suggest a course of action.

That looks sensible to me as well

Thanks

-- 
~Vinod