Date: Sat, 3 Dec 2005 14:44:58 +0300 (MSK)
From: vitalhome@rbcmail.ru
Message-Id: <200512031144.jB3BiwRG048640@www4.pochta.ru>
To: greg@kroah.com
Cc: linux-kernel@vger.kernel.org, dpervushin@gmail.com
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Subject: Re: [PATCH 2.6-git] SPI core refresh
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> > >>- it's more adapted for use in real-time environments
> > >>
> > >I still do not see why you are stating this.  Why do you say this?
> > >
> > Due to possible priority inversion problems in David's core.
> 
> I am still not convinced of your statements here, sorry.  Specifics
> please.

So, again, David's write_then_read function which is the basic one for all the synchronous 
transfers uses single static pointer to kmalloc'ed buffer and protects its usage by 
semaphores. If there are multiple controllers onboard, this serialization is suboptimal 
and may cause priority inversion if, for instance, two threads with different priorities 
will use this function at the same time.

Vitaly
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