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From: "Rajat Jain" <rajat.noida.india@gmail.com>
To: "Rik van Riel" <riel@surriel.com>
Cc: "Rick Brown" <rick.brown.3@gmail.com>,
	kernelnewbies@nl.linux.org, linux-kernel@vger.kernel.org
Subject: Re: Spinlock query
Date: Wed, 30 Aug 2006 11:01:43 +0530	[thread overview]
Message-ID: <b115cb5f0608292231r1a3c47c8r8980b32e838ff964@mail.gmail.com> (raw)
In-Reply-To: <44F501B3.9070200@surriel.com>

On 8/30/06, Rik van Riel <riel@surriel.com> wrote:
> Rick Brown wrote:
> > Hi,
> >
> > In my driver (Process context), I have written the following code:
> >
> > --------------------------------------------
> > spin_lock(lock)
> > ...
> > //Critical section to manipulate driver data
>
> ... interrupt hits here
>     interrupt handler tries to grab the spinlock, which is already taken
>     *BOOM*
>
> > spin_u lock(lock)
> > ---------------------------------------------
> >

The interrupt handler TRIES to grab the spinlock, which is already
taken. Why will it "BOOM"? Wouldn't the interrupt handler busy wait,
waiting for the lock?

Am I missing something here?

Rajat

> > I have written similar code in my interrupt handler (Interrupt
> > context). The driver data is not accessed from anywhere else. Is my
> > code safe from any potential concurrency issues? Is there a need to
> > use spin_lock_irqsave()? In both the places?
>
> You need to use spin_lock_irqsave() from process context.
>  From the interrupt handler itself it doesn't hurt, but it
> shouldn't matter much since interrupt handlers should not
> get preempted.

  reply	other threads:[~2006-08-30  5:31 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-30  2:12 Spinlock query Rick Brown
2006-08-30  2:12 ` Rick Brown
2006-08-30  3:10 ` Rik van Riel
2006-08-30  5:31   ` Rajat Jain [this message]
2006-08-30  6:04     ` Vin
2006-08-30 12:03     ` Rik van Riel
     [not found]   ` <fa2bedd60608292159ra9fce70wd1dbc8231d9c052c@mail.gmail.com>
2006-09-01  2:31     ` Rajat Jain

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