From: Robert Love <rml@tech9.net>
To: sridharv@ufl.edu
Cc: linux-kernel@vger.kernel.org
Subject: Re: interrupt - spin lock question
Date: 04 Mar 2002 00:27:49 -0500 [thread overview]
Message-ID: <1015219669.868.35.camel@phantasy> (raw)
In-Reply-To: <1015219129.3c8303b9e87a7@webmail.health.ufl.edu>
In-Reply-To: <1015219129.3c8303b9e87a7@webmail.health.ufl.edu>
On Mon, 2002-03-04 at 00:18, sridharv@ufl.edu wrote:
> I have a question related to spin locking on UP systems.Before that I would
> like to point out my understanding of the background stuff
> 1. spinlocks shud be used in intr handlers
> 2. interrupts can preempt kernel code
> 3. spinlocks are turned to empty when kernel is compiled without SMP support.
This is right.
> If a particular driver is running( not the intr handler part) and at this time
> an interrupt occurs. The handler has to be invoked now. Won't the preemption
> cause race conditions/inconsistencies? Is any other mechanism used?
> Pl correct me if I have not understood any part of this correctly
> -sridhar
Right, that is why you would use a spin_lock ! :)
Further, you would want to use a spin_lock_irq and related friends. The
irq disable prevents the race wrt interrupts and the spin_lock prevents
racing wrt SMP.
Robert Love
next prev parent reply other threads:[~2002-03-04 5:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-04 5:18 sridharv
2002-03-04 5:27 ` Robert Love [this message]
2002-03-04 6:33 ` sridharv
2002-03-04 7:19 ` Robert Love
2002-03-04 6:32 ` Kittur Sameer
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