linux-kernel - Re: [PATCH -rt] Updates-from-Jon-Masters-for-hwlat

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Date:	Mon, 2 Nov 2009 20:46:11 +0100
From:	John Kacur <jkacur@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, Jon Masters <jcm@...hat.com>,
	linux-rt-users@...r.kernel.org,
	Clark Williams <williams@...hat.com>
Subject: Re: [PATCH -rt] Updates-from-Jon-Masters-for-hwlat_detector.c.patch

On Mon, Nov 2, 2009 at 4:43 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> Hi,
>
> On Fri, 23 Oct 2009, John Kacur wrote:
>> I took Jon Masters' latest hwlat_detector patch for upstream, and grabbed
>> the bits that aren't currently in -rt. The patch is fairly small.
>>
>> Please consider it for the next -rt release.
>
> Not really.
>
>> diff --git a/drivers/misc/hwlat_detector.c b/drivers/misc/hwlat_detector.c
>> index be6553f..7191e17 100644
>> --- a/drivers/misc/hwlat_detector.c
>> +++ b/drivers/misc/hwlat_detector.c
>> @@ -262,6 +262,8 @@ static int get_sample(void *unused)
>>               /* Keep a running maximum ever recorded hardware latency */
>>               if (sample > data.max_sample)
>>                       data.max_sample = sample;
>> +
>> +             wake_up(&data.wq); /* wake up reader(s) */
>>       }
>>
>>       ret = 0;
>> @@ -299,8 +301,6 @@ static int kthread_fn(void *unused)
>>                       goto err_out;
>>               }
>>
>> -             wake_up(&data.wq); /* wake up reader(s) */
>> -
>
> This reverts -rt commit 5fc485f6341c177e9d5f641c6fb9e33ca465aa84.
>
> CONFIG_DEBUG_SPINLOCK_SLEEP resp. CONFIG_DEBUG_PREEMPT will tell you
> why this is a bad idea on -rt :)
>
> Thanks,
>
>        tglx
> --

Ugh. Thanks for catching that. To be honest not sure how it happened,
so it must be my fault. :)

Updated patch just adds the error checking from Jon Masters then,
patched against -rt.

View attachment "0001-Updates-from-Jon-Masters-for-hwlat_detector.c.patch" of type "text/x-diff" (1651 bytes)