Hi Toshi, On Thu, 2012-03-08 at 14:01 -0700, Toshi Kani wrote: > On Wed, 2012-03-07 at 11:48 -0800, Alok Kataria wrote: > > Len, anyone else, > > > > Any comments on this one ? This fixes a important bug during cpu hotadd > > where the kernel fails to recognize all the newly added cpus. > > > > Thanks, > > Alok > > > > > > On Wed, 2012-02-15 at 16:06 -0800, Petr Vandrovec wrote: > > > From: Petr Vandrovec <petr@xxxxxxxxxx> > > > > > > When processor is being hot-added to the system, acpi_map_lsapic invokes > > > ACPI _MAT method to find APIC ID and flags, verifies that returned structure > > > is indeed ACPI's local APIC structure, and that flags contain MADT_ENABLED > > > bit. Then saves APIC ID, frees structure - and accesses structure when > > > computing arguments for acpi_register_lapic call. Which sometime leads > > > to acpi_register_lapic call being made with second argument zero, failing > > > to bring processor online with error 'Unable to map lapic to logical cpu > > > number'. > > > > > > As lapic->lapic_flags & ACPI_MADT_ENABLED was already confirmed to be non-zero > > > few lines above, we can just pass unconditional ACPI_MADT_ENABLED to the > > > acpi_register_lapic. > > > > > > Thanks, Petr > > > > > > Signed-off-by: Petr Vandrovec <petr@xxxxxxxxxx> > > > Signed-off-by: Alok Kataria <akataria@xxxxxxxxxx> > > > > > > > > > diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c > > > index ce664f3..a4a0901 100644 > > > --- a/arch/x86/kernel/acpi/boot.c > > > +++ b/arch/x86/kernel/acpi/boot.c > > > @@ -650,7 +650,7 @@ static int __cpuinit _acpi_map_lsapic(acpi_handle handle, int *pcpu) > > > goto free_tmp_map; > > > > > > cpumask_copy(tmp_map, cpu_present_mask); > > > - acpi_register_lapic(physid, lapic->lapic_flags & ACPI_MADT_ENABLED); > > > + acpi_register_lapic(physid, ACPI_MADT_ENABLED); > > The change looks good. I suggest you also add the following line to > prevent such bug in future. > > kfree(buffer.pointer); > buffer.length = ACPI_ALLOCATE_BUFFER; > buffer.pointer = NULL; > + lapic = NULL; That's a good suggestion, below is the updated patch. Thanks !! -- From: Petr Vandrovec <petr@xxxxxxxxxx> When processor is being hot-added to the system, acpi_map_lsapic invokes ACPI _MAT method to find APIC ID and flags, verifies that returned structure is indeed ACPI's local APIC structure, and that flags contain MADT_ENABLED bit. Then saves APIC ID, frees structure - and accesses structure when computing arguments for acpi_register_lapic call. Which sometime leads to acpi_register_lapic call being made with second argument zero, failing to bring processor online with error 'Unable to map lapic to logical cpu number'. As lapic->lapic_flags & ACPI_MADT_ENABLED was already confirmed to be non-zero few lines above, we can just pass unconditional ACPI_MADT_ENABLED to the acpi_register_lapic. Signed-off-by: Petr Vandrovec <petr@xxxxxxxxxx> Signed-off-by: Alok N Kataria <akataria@xxxxxxxxxx> Cc : Toshi Kani <toshi.kani@xxxxxx> Index: linux-2.6/arch/x86/kernel/acpi/boot.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/acpi/boot.c 2012-01-24 14:48:56.000000000 -0800 +++ linux-2.6/arch/x86/kernel/acpi/boot.c 2012-03-08 13:25:39.000000000 -0800 @@ -642,6 +642,7 @@ static int __cpuinit _acpi_map_lsapic(ac kfree(buffer.pointer); buffer.length = ACPI_ALLOCATE_BUFFER; buffer.pointer = NULL; + lapic = NULL; if (!alloc_cpumask_var(&tmp_map, GFP_KERNEL)) goto out; @@ -650,7 +651,7 @@ static int __cpuinit _acpi_map_lsapic(ac goto free_tmp_map; cpumask_copy(tmp_map, cpu_present_mask); - acpi_register_lapic(physid, lapic->lapic_flags & ACPI_MADT_ENABLED); + acpi_register_lapic(physid, ACPI_MADT_ENABLED); /* * If mp_register_lapic successfully generates a new logical cpu -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
