From: James Bottomley <James.Bottomley@steeleye.com>
To: Grant Grundler <grundler@parisc-linux.org>
Cc: PARISC list <parisc-linux@lists.parisc-linux.org>
Subject: Re: [parisc-linux] init_idle and local_irq_save
Date: 29 Mar 2004 11:17:19 -0500 [thread overview]
Message-ID: <1080577040.1804.9.camel@mulgrave> (raw)
In-Reply-To: <20040329160357.GA31448@colo.lackof.org>
On Mon, 2004-03-29 at 11:03, Grant Grundler wrote:
> o local_irq_save()/local_irq_restore are called without an
> obvious local_irq_disable() call in between. Is this really
> needed for some other reason or is the local_irq_disable() missing?
local_irq_save() does do an irq disable. You're thinking of
local_save_flags() which only saves the flags but doesn't disable
interrupts.
> o double_rq_lock() acquires the locks with lowest address first.
> double_rq_unlock() does not release those in the inverse order.
> Is that a problem?
> I'm just nervous since I didn't see the local_irq_disable()
> in init_idle() which would guarantee both unlock's happen atomically.
No. The deadlock potential comes only from lock acquisition order, not
lock release order: nothing can block a lock release from proceeding.
James
next prev parent reply other threads:[~2004-03-29 16:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-29 16:03 [parisc-linux] init_idle and local_irq_save Grant Grundler
2004-03-29 16:17 ` James Bottomley [this message]
2004-03-29 16:31 ` Matthew Wilcox
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