Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758678AbXEJF0u (ORCPT ); Thu, 10 May 2007 01:26:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757843AbXEJF02 (ORCPT ); Thu, 10 May 2007 01:26:28 -0400 Received: from ozlabs.org ([203.10.76.45]:49204 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757494AbXEJF00 (ORCPT ); Thu, 10 May 2007 01:26:26 -0400 To: , CC: Rusty Russell , Andrew Morton From: Benjamin Herrenschmidt Date: Thu, 10 May 2007 15:25:58 +1000 Subject: [PATCH 2/3] Add hard_irq_disable() Message-Id: <20070510052622.3E8D5DDF4B@ozlabs.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2320 Lines: 50 Some architectures, like powerpc, implement lazy disabling of interrupts. That means that on those, local_irq_disable() doesn't actually disable interrupts on the CPU, but only sets some per CPU flag which cause them to be disabled only if an interrupt actually occurs. However, in some cases, such as stop_machine, we really want interrupts to be fully disabled. For example, I have code using stop machine to do ECC error injection, used to verify operations of the ECC hardware, that sort of thing. It really needs to make sure that nothing is actually writing to memory while the injection happens. Similar examples can be found in other low level bits and pieces. This patch implements a generic hard_irq_disable() function which is meant to be called -after- local_irq_disable() and ensures that interrupts are fully disabled on that CPU. The default implementation is a nop, though powerpc does already provide an appropriate one. Signed-off-by: Benjamin Herrenschmidt include/linux/interrupt.h | 10 ++++++++++ 1 file changed, 10 insertions(+) Index: linux-cell/include/linux/interrupt.h =================================================================== --- linux-cell.orig/include/linux/interrupt.h 2007-05-10 14:51:22.000000000 +1000 +++ linux-cell/include/linux/interrupt.h 2007-05-10 15:18:04.000000000 +1000 @@ -241,6 +241,16 @@ static inline void __deprecated save_and #define save_and_cli(x) save_and_cli(&x) #endif /* CONFIG_SMP */ +/* Some architectures might implement lazy enabling/disabling of + * interrupts. In some cases, such as stop_machine, we might want + * to ensure that after a local_irq_disable(), interrupts have + * really been disabled in hardware. Such architectures need to + * implement the following hook. + */ +#ifndef hard_irq_disable +#define hard_irq_disable() do { } while(0) +#endif + /* PLEASE, avoid to allocate new softirqs, if you need not _really_ high frequency threaded job scheduling. For almost all the purposes tasklets are more than enough. F.e. all serial device BHs et - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/