linux-kernel - Re: [PATCH 2/8] staging: omap-thermal: use spin_lock

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Message-ID: <20130318195837.GS9189@mwanda>
Date:	Mon, 18 Mar 2013 22:58:37 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Eduardo Valentin <eduardo.valentin@...com>
Cc:	gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH 2/8] staging: omap-thermal: use spin_lock_irqsave inside
 IRQ handler

On Mon, Mar 18, 2013 at 03:38:38PM -0400, Eduardo Valentin wrote:
> On 18-03-2013 15:16, Dan Carpenter wrote:
> >On Mon, Mar 18, 2013 at 10:59:10AM -0400, Eduardo Valentin wrote:
> >>Even if the IRQ is not firing because it is ONE_SHOT and disable
> >>at INTC level, the IRQ handler must use spin_lock_irqsave.
> >>It is necessary to disable IRQs from the current
> >>CPU while it is holding a spin_lock which is need.
> >>
> >
> >Gar...  I think I was just totally wrong on this.  I think your
> >original code was fine.  Sorry Eduardo and Greg.
> >
> >This is a threaded IRQ so the regular spin_lock is fine or even the
> >mutex would have been.
> 
> In fact it is. But I rather prefer to use spinlocks there, just to
> keep the irq handler sane, even if it is moved to non-threaded IRQ.

Yep.  I'd agree there.

> 
> >
> >IRQ_ONESHOT is about triggering a second IRQ before the first one
> >has been finished, btw.
> 
> It is, and that gets done by masking the IRQ at INTC level.
> 
> >
> >I am an idiot.
> 
> 
> Not really. Thanks for your time reviewing the driver.
> 
>  I will resend this series. Drop this one and split patch 4/8 into
> two I think (one for moving files, one for renaming functions)

Great.  Much appreciated.

regards,
dan carpenter

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