From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 4ADDBDDEFE for ; Thu, 10 May 2007 18:44:34 +1000 (EST) Subject: Re: [PATCH 1/3] powerpc: Fixup hard_irq_disable semantics From: Benjamin Herrenschmidt To: Geert Uytterhoeven In-Reply-To: References: <20070510052620.EC36DDDF92@ozlabs.org> Content-Type: text/plain Date: Thu, 10 May 2007 18:44:22 +1000 Message-Id: <1178786662.14928.229.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Andrew Morton , Rusty Russell , linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2007-05-10 at 09:44 +0200, Geert Uytterhoeven wrote: > On Thu, 10 May 2007, Benjamin Herrenschmidt wrote: > > This patch renames the raw hard_irq_{enable,disable} into > > __hard_irq_{enable,disable} and introduces a higher level > > hard_irq_disable() function that can be used by any code > > to enforce that IRQs are fully disabled, not only lazy > > disabled. > > Why did you rename hard_irq_enable() too? > > Isn't it more logical to have high-level hard_irq_disable() and > hard_irq_enable(), and a special low-level __hard_irq_disable()? Not really. If you see my subsequent patch, the idea is to introduce a single generic hard_irq_disable() which is meant to be called with irqs already disabled (that is within a local_irq_disable section) to enforce that if the arch does lazy disabling, it gets hard disabled at this point. If we start adding hard_irq_enable() we end up in a can of worms: - Do we want all the full set of save/restore etc... ? - What if somebody does hard_enable while we are soft-disabled -and- have been hard disabled because of a pending interrupt ? - What's the point ? :-) So overall, I want to keep the semantics as simple as they can be. Maybe I can even add some WARN_ON() to make sure we are in a local_irq_disable'd section even in the generic one instead of just a NOP to enfore that. Cheers, Ben.