From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161207AbWJLGjo (ORCPT ); Thu, 12 Oct 2006 02:39:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932506AbWJLGjo (ORCPT ); Thu, 12 Oct 2006 02:39:44 -0400 Received: from smtp.osdl.org ([65.172.181.4]:9908 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1161207AbWJLGjn (ORCPT ); Thu, 12 Oct 2006 02:39:43 -0400 Date: Wed, 11 Oct 2006 23:39:25 -0700 From: Andrew Morton To: Peter Zijlstra Cc: linux-kernel , sfr@canb.auug.org.au, Ingo Molnar Subject: Re: [PATCH] lockdep: annotate i386 apm Message-Id: <20061011233925.c9ba117a.akpm@osdl.org> In-Reply-To: <1160633180.2006.94.camel@taijtu> References: <1160574022.2006.82.camel@taijtu> <20061011141813.79fb278f.akpm@osdl.org> <1160633180.2006.94.camel@taijtu> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 12 Oct 2006 08:06:20 +0200 Peter Zijlstra wrote: > #define local_irq_restore(flags) \ > do { \ > if (raw_irqs_disabled_flags(flags)) { \ > raw_local_irq_restore(flags); \ > trace_hardirqs_off(); \ > } else { \ > trace_hardirqs_on(); \ > raw_local_irq_restore(flags); \ > } \ > } while (0) > > So, say interrupts were enabled when entering apm_bios_call*(); you now > save that in flags, disable interrupts, and enable them again. > Upon reaching local_irq_restore(), we'll hit the else branch with irq's > enabled and call trace_hardirqs_on(), which goes EEEK! I'd assumed lockdep was less stupid than that ;) This? Seems a bit overdone.. --- a/arch/i386/kernel/apm.c~lockdep-annotate-i386-apm +++ a/arch/i386/kernel/apm.c @@ -540,12 +540,6 @@ static inline void apm_restore_cpus(cpum * Also, we KNOW that for the non error case of apm_bios_call, there * is no useful data returned in the low order 8 bits of eax. */ -#define APM_DO_CLI \ - if (apm_info.allow_ints) \ - local_irq_enable(); \ - else \ - local_irq_disable(); - #ifdef APM_ZERO_SEGS # define APM_DECL_SEGS \ unsigned int saved_fs; unsigned int saved_gs; @@ -583,11 +577,12 @@ static u8 apm_bios_call(u32 func, u32 eb u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, u32 *esi) { APM_DECL_SEGS - unsigned long flags; cpumask_t cpus; int cpu; struct desc_struct save_desc_40; struct desc_struct *gdt; + int enable_irqs = 0; + int disable_irqs = 0; cpus = apm_save_cpus(); @@ -596,12 +591,26 @@ static u8 apm_bios_call(u32 func, u32 eb save_desc_40 = gdt[0x40 / 8]; gdt[0x40 / 8] = bad_bios_desc; - local_save_flags(flags); - APM_DO_CLI; + if (apm_info.allow_ints) { + if (irqs_disabled()) { + local_irq_enable(); + disable_irqs = 1; + } + } else { + if (!irqs_disabled()) { + local_irq_disable(); + enable_irqs = 1; + } + } + + APM_DO_SAVE_SEGS; apm_bios_call_asm(func, ebx_in, ecx_in, eax, ebx, ecx, edx, esi); APM_DO_RESTORE_SEGS; - local_irq_restore(flags); + if (disable_irqs) + local_irq_disable(); + if (enable_irqs) + local_irq_enable(); gdt[0x40 / 8] = save_desc_40; put_cpu(); apm_restore_cpus(cpus); @@ -627,11 +636,12 @@ static u8 apm_bios_call_simple(u32 func, { u8 error; APM_DECL_SEGS - unsigned long flags; cpumask_t cpus; int cpu; struct desc_struct save_desc_40; struct desc_struct *gdt; + int enable_irqs = 0; + int disable_irqs = 0; cpus = apm_save_cpus(); @@ -640,12 +650,25 @@ static u8 apm_bios_call_simple(u32 func, save_desc_40 = gdt[0x40 / 8]; gdt[0x40 / 8] = bad_bios_desc; - local_save_flags(flags); - APM_DO_CLI; + if (apm_info.allow_ints) { + if (irqs_disabled()) { + local_irq_enable(); + disable_irqs = 1; + } + } else { + if (!irqs_disabled()) { + local_irq_disable(); + enable_irqs = 1; + } + } + APM_DO_SAVE_SEGS; error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax); APM_DO_RESTORE_SEGS; - local_irq_restore(flags); + if (disable_irqs) + local_irq_disable(); + if (enable_irqs) + local_irq_enable(); gdt[0x40 / 8] = save_desc_40; put_cpu(); apm_restore_cpus(cpus); _