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[PATCH] i386 boottime for_each_cpu broken

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for_each_cpu walks through all processors in cpu_possible_map, which is
defined as cpu_callout_map on i386 and isn't initialised until all
processors have been booted. This breaks things which do for_each_cpu
iterations early during boot. So, define cpu_possible_map as a bitmap with
NR_CPUS bits populated. This was triggered by a patch i'm working on which
does alloc_percpu before bringing up secondary processors.

From: Alexander Nyberg <alexn@telia.com>

i386-boottime-for_each_cpu-broken.patch
i386-boottime-for_each_cpu-broken-fix.patch

The SMP version of __alloc_percpu checks the cpu_possible_map before
allocating memory for a certain cpu.  With the above patches the BSP cpuid
is never set in cpu_possible_map which breaks CONFIG_SMP on uniprocessor
machines (as soon as someone tries to dereference something allocated via
__alloc_percpu, which in fact is never allocated since the cpu is not set
in cpu_possible_map).

Signed-off-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Zwane Mwaikambo
2005-09-03 15:56:51 -07:00
committed by Linus Torvalds
parent d7271b14b2
commit 4ad8d38342
4 changed files with 14 additions and 2 deletions
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3
arch/i386/kernel/smpboot.c
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@@ -88,6 +88,8 @@ EXPORT_SYMBOL(cpu_online_map);
cpumask_t cpu_callin_map;
cpumask_t cpu_callout_map;
EXPORT_SYMBOL(cpu_callout_map);
cpumask_t cpu_possible_map;
EXPORT_SYMBOL(cpu_possible_map);
static cpumask_t smp_commenced_mask;
/* TSC's upper 32 bits can't be written in eariler CPU (before prescott), there
@@ -1265,6 +1267,7 @@ void __devinit smp_prepare_boot_cpu(void)
cpu_set(smp_processor_id(), cpu_online_map);
cpu_set(smp_processor_id(), cpu_callout_map);
cpu_set(smp_processor_id(), cpu_present_map);
cpu_set(smp_processor_id(), cpu_possible_map);
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
}