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Subject[PATCH, v2] i386/bigsmp: eliminate false warnings regarding logical APIC ID mismatches
These warnings (generally one per CPU) are a result of initializing
x86_cpu_to_logical_apicid while apic_default is still in use, but the
check in setup_local_APIC() being done when apic_bigsmp was already
used as an override in default_setup_apic_routing():

Overriding APIC driver with bigsmp
Enabling APIC mode: Physflat. Using 5 I/O APICs
------------[ cut here ]------------
WARNING: at .../arch/x86/kernel/apic/apic.c:1239 setup_local_APIC+0x137/0x46b()
Hardware name: ...
CPU0 logical APIC ID: 1 != 0
Pid: 1, comm: swapper Not tainted 3.0.1-2011-08-09-jb #2
Call Trace:
[<c1005f91>] try_stack_unwind+0x1b1/0x1f0
[<c1004cc7>] dump_trace+0x47/0x110
[<c1005b0b>] show_trace_log_lvl+0x4b/0x60
[<c1005b38>] show_trace+0x18/0x20
[<c1261435>] dump_stack+0x6d/0x72
[<c10355f7>] warn_slowpath_common+0x77/0xb0
[<c10356c3>] warn_slowpath_fmt+0x33/0x40
[<c13fda81>] setup_local_APIC+0x137/0x46b
[<c13d1733>] native_smp_prepare_cpus+0x108/0x1cd
[<c13c61ff>] kernel_init+0x37/0x12c
[<c1264826>] kernel_thread_helper+0x6/0xd
---[ end trace 4eaa2a86a8e2da22 ]---
...
CPU 1 irqstacks, hard=f1c9a000 soft=f1c9c000
Booting Node 0, Processors #1
smpboot cpu 1: start_ip = 9e000
Initializing CPU#1
------------[ cut here ]------------
WARNING: at .../arch/x86/kernel/apic/apic.c:1239 setup_local_APIC+0x137/0x46b()
Hardware name: ...
CPU1 logical APIC ID: 2 != 8
...

Fix this (for the time being, i.e. until x86_32_early_logical_apicid()
will get removed again, as Tejun says ought to be possible) by
overriding the previously stored values at the point where the APIC
driver gets overridden.

v2: Move this and the pre-existing override logic into
arch/x86/kernel/apic/bigsmp_32.c.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org (2.6.39 and onwards)

---
arch/x86/include/asm/apic.h | 2 +-
arch/x86/kernel/apic/bigsmp_32.c | 20 ++++++++++++++++----
arch/x86/kernel/apic/probe_32.c | 10 ++--------
3 files changed, 19 insertions(+), 13 deletions(-)

--- 3.1-rc8/arch/x86/include/asm/apic.h
+++ 3.1-rc8-i386-bigsmp-early-lapicid-override/arch/x86/include/asm/apic.h
@@ -495,7 +495,7 @@ static inline void default_wait_for_init
return;
}

-extern struct apic *generic_bigsmp_probe(void);
+extern void generic_bigsmp_probe(void);


#ifdef CONFIG_X86_LOCAL_APIC
--- 3.1-rc8/arch/x86/kernel/apic/bigsmp_32.c
+++ 3.1-rc8-i386-bigsmp-early-lapicid-override/arch/x86/kernel/apic/bigsmp_32.c
@@ -255,12 +255,24 @@ static struct apic apic_bigsmp = {
.x86_32_early_logical_apicid = bigsmp_early_logical_apicid,
};

-struct apic * __init generic_bigsmp_probe(void)
+void __init generic_bigsmp_probe(void)
{
- if (probe_bigsmp())
- return &apic_bigsmp;
+ unsigned int cpu;

- return NULL;
+ if (!probe_bigsmp())
+ return;
+
+ apic = &apic_bigsmp;
+
+ for_each_possible_cpu(cpu) {
+ if (early_per_cpu(x86_cpu_to_logical_apicid,
+ cpu) == BAD_APICID)
+ continue;
+ early_per_cpu(x86_cpu_to_logical_apicid, cpu) =
+ bigsmp_early_logical_apicid(cpu);
+ }
+
+ pr_info("Overriding APIC driver with %s\n", apic_bigsmp.name);
}

apic_driver(apic_bigsmp);
--- 3.1-rc8/arch/x86/kernel/apic/probe_32.c
+++ 3.1-rc8-i386-bigsmp-early-lapicid-override/arch/x86/kernel/apic/probe_32.c
@@ -200,14 +200,8 @@ void __init default_setup_apic_routing(v
* - we find more than 8 CPUs in acpi LAPIC listing with xAPIC support
*/

- if (!cmdline_apic && apic == &apic_default) {
- struct apic *bigsmp = generic_bigsmp_probe();
- if (bigsmp) {
- apic = bigsmp;
- printk(KERN_INFO "Overriding APIC driver with %s\n",
- apic->name);
- }
- }
+ if (!cmdline_apic && apic == &apic_default)
+ generic_bigsmp_probe();
#endif

if (apic->setup_apic_routing)




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