From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161522AbWJLGGL (ORCPT ); Thu, 12 Oct 2006 02:06:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161531AbWJLGGL (ORCPT ); Thu, 12 Oct 2006 02:06:11 -0400 Received: from amsfep17-int.chello.nl ([213.46.243.15]:59872 "EHLO amsfep19-int.chello.nl") by vger.kernel.org with ESMTP id S1161522AbWJLGGJ (ORCPT ); Thu, 12 Oct 2006 02:06:09 -0400 Subject: Re: [PATCH] lockdep: annotate i386 apm From: Peter Zijlstra To: Andrew Morton Cc: linux-kernel , sfr@canb.auug.org.au, Ingo Molnar In-Reply-To: <20061011141813.79fb278f.akpm@osdl.org> References: <1160574022.2006.82.camel@taijtu> <20061011141813.79fb278f.akpm@osdl.org> Content-Type: text/plain Date: Thu, 12 Oct 2006 08:06:20 +0200 Message-Id: <1160633180.2006.94.camel@taijtu> Mime-Version: 1.0 X-Mailer: Evolution 2.6.3 (2.6.3-1.fc5.5) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-10-11 at 14:18 -0700, Andrew Morton wrote: > On Wed, 11 Oct 2006 15:40:22 +0200 > Peter Zijlstra wrote: > > > > > Lockdep doesn't like to enable interrupts when they are enabled already. > > > > ... > > > > --- linux-2.6.18.noarch.orig/arch/i386/kernel/apm.c > > +++ linux-2.6.18.noarch/arch/i386/kernel/apm.c > > @@ -539,11 +539,22 @@ 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(); > > +#define APM_DO_CLI \ > > + do { \ > > + if (apm_info.allow_ints) { \ > > + if (irqs_disabled_flags(flags)) \ > > + local_irq_enable(); \ > > + } else \ > > + local_irq_disable(); \ > > + } while (0) > > + > > +#define APM_DO_STI \ > > + do { \ > > + if (irqs_disabled_flags(flags)) \ > > + local_irq_disable(); \ > > + else if (irqs_disabled()) \ > > + local_irq_enable(); \ > > + } while (0) > > > > #ifdef APM_ZERO_SEGS > > # define APM_DECL_SEGS \ > > @@ -600,7 +611,7 @@ static u8 apm_bios_call(u32 func, u32 eb > > 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); > > + APM_DO_STI; > > gdt[0x40 / 8] = save_desc_40; > > put_cpu(); > > apm_restore_cpus(cpus); > > @@ -644,7 +655,7 @@ static u8 apm_bios_call_simple(u32 func, > > APM_DO_SAVE_SEGS; > > error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax); > > APM_DO_RESTORE_SEGS; > > - local_irq_restore(flags); > > + APM_DO_STI; > > gdt[0x40 / 8] = save_desc_40; > > put_cpu(); > > apm_restore_cpus(cpus); > > ick. > > Does this work? > > --- 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; > @@ -596,8 +590,9 @@ 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; > + local_irq_save(flags); > + if (apm_info.allow_ints) > + local_irq_enable(); > APM_DO_SAVE_SEGS; > apm_bios_call_asm(func, ebx_in, ecx_in, eax, ebx, ecx, edx, esi); > APM_DO_RESTORE_SEGS; > @@ -640,8 +635,9 @@ 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; > + local_irq_save(flags); > + if (apm_info.allow_ints) > + local_irq_enable(); > APM_DO_SAVE_SEGS; > error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax); > APM_DO_RESTORE_SEGS; > _ #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!