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Subject: Re: [PATCH] staging: pi433: add descriptions for mutex locks
To:     Valentin Vidic <Valentin.Vidic@CARNet.hr>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?Q?Simon_Sandstr=c3=b6m?= <simon@nikanor.nu>,
        Marcus Wolf <linux@Wolf-Entwicklungen.de>,
        =?UTF-8?Q?Luca_S=c3=b6the?= <luca@acul.me>,
        Marcin Ciupak <marcin.s.ciupak@gmail.com>,
        Michael Panzlaff <michael.panzlaff@fau.de>,
        Derek Robson <robsonde@gmail.com>, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org
References: <20180323094725.4904-1-Valentin.Vidic@CARNet.hr>
 <d263c605-f652-fe24-2034-c699f2d27693@smarthome-wolf.de>
 <20180323114254.GL31333@gavran.carpriv.carnet.hr>
From:   Marcus Wolf <marcus.wolf@smarthome-wolf.de>
Message-ID: <9442615c-5606-328a-f8cc-ad389af55ee3@smarthome-wolf.de>
Date:   Fri, 23 Mar 2018 16:38:50 +0100
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Hi Valentin,

I had no time to work on the code for monthes now and the memorisation
of my thoughts when I was programming that (approx. one year ago) is
quite pale.

As far as I remember, I read something, that the fifo has an integrated
protection, so no external protection is needed. But absolutely unsure.

If I will find some time within the next days, I'll have a look at the
code and try to recall.

But the most important thing already took place: We started thinking
about it :-)

Thanks,

Marcus

Am 23.03.2018 um 12:42 schrieb Valentin Vidic:
> On Fri, Mar 23, 2018 at 11:22:39AM +0100, Marcus Wolf wrote:
>> could you please decribe in short words, why you think, that hte lock
>> isn't obsolete?
>>
>> I wasn't sure, but close to remove the lock. That's why I putted the
>> comment.
> 
> Sure, if pi433_tx_thread runs on one CPU it might be possible
> to call pi433_write concurrently on another CPU and they would
> both modify tx_fifo.  But maybe there is some other protection
> in place that would prevent this?
> 

-- 
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Geschäftsführer: Marcus Wolf