Messages in this thread Patch in this message | | | Date | Wed, 11 Oct 2006 23:39:25 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] lockdep: annotate i386 apm |
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On Thu, 12 Oct 2006 08:06:20 +0200 Peter Zijlstra <a.p.zijlstra@chello.nl> 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); _ - 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/
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