[8498] in linux-scsi channel archive
Re: Semaphore lock up in SMP environment
daemon@ATHENA.MIT.EDU (Alan Cox)
Mon Mar 27 13:28:07 2000
To: Venkateshr@ami.com (Venkatesh Ramamurthy)
Date: Mon, 27 Mar 2000 18:58:49 +0100 (BST)
Cc: linux-scsi@vger.rutgers.edu, linux-smp@vger.rutgers.edu,
linux-kernel@vger.rutgers.edu, dave@gcom.com ('David Grothe')
In-Reply-To: <1355693A51C0D211B55A00105ACCFE64628783@ATL_MS1> from "Venkatesh Ramamurthy" at Mar 27, 2000 11:05:01 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
> I call up() in our ISR to release the semaphore flag . Since down() in SMP
> disable interrupts , there is no way my ISR is fired which releases the
> flag
> and so freezes the system.
Down does not disable interrupts that I can see, except momentarily when
checking the queues, and it restores them before it yields CPU time. On
exit the irqs are enabled.
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