From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758920AbYJKPna (ORCPT ); Sat, 11 Oct 2008 11:43:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753519AbYJKPnW (ORCPT ); Sat, 11 Oct 2008 11:43:22 -0400 Received: from smtp-out003.kontent.com ([81.88.40.217]:50414 "EHLO smtp-out003.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752808AbYJKPnW (ORCPT ); Sat, 11 Oct 2008 11:43:22 -0400 From: Oliver Neukum Organization: Novell To: Andrey Borzenkov Subject: Re: when spin_lock_irq (as opposed to spin_lock_irqsave) is appropriate? Date: Sat, 11 Oct 2008 17:41:53 +0200 User-Agent: KMail/1.9.9 Cc: Linux Kernel Mailing List References: <200810111929.01927.arvidjaar@mail.ru> In-Reply-To: <200810111929.01927.arvidjaar@mail.ru> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200810111741.53404.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Samstag, 11. Oktober 2008 17:29:01 schrieb Andrey Borzenkov: > Logically, one piece of kernel code has no way to know whether another > piece of kernel code (or may be hard-/firmware) has disabled some > interrupt line. So it looks like spin_lock_irq should not even exist, > except may be for very specific cases (where we are sure no other piece > of kernel code may run concurrently)? > > Sorry for stupid question, I an not actually a HW type of person ... > This has no connection with individual irq lines. It's about being able to sleep. Kernel code usually knows whether it can sleep. If it knows to be able to sleep it can use spin_lock_irq() which is more efficient than spin_lock_irqsave() Regards Oliver