forked from luck/tmp_suning_uos_patched
x86, hotplug: Serialize CPU hotplug to avoid bringup concurrency issues
When testing cpu hotplug code on 32-bit we kept hitting the "CPU%d: Stuck ??" message due to multiple cores concurrently accessing the cpu_callin_mask, among others. Since these codepaths are not protected from concurrent access due to the fact that there's no sane reason for making an already complex code unnecessarily more complex - we hit the issue only when insanely switching cores off- and online - serialize hotplugging cores on the sysfs level and be done with it. [ v2.1: fix !HOTPLUG_CPU build ] Cc: <stable@kernel.org> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> LKML-Reference: <20100819181029.GC17171@aftab> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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@ -245,6 +245,11 @@ config ARCH_HWEIGHT_CFLAGS
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config KTIME_SCALAR
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config KTIME_SCALAR
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def_bool X86_32
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def_bool X86_32
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config ARCH_CPU_PROBE_RELEASE
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def_bool y
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depends on HOTPLUG_CPU
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source "init/Kconfig"
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source "init/Kconfig"
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source "kernel/Kconfig.freezer"
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source "kernel/Kconfig.freezer"
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@ -90,6 +90,25 @@ DEFINE_PER_CPU(int, cpu_state) = { 0 };
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static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
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static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
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#define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x))
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#define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x))
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#define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p))
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#define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p))
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/*
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* We need this for trampoline_base protection from concurrent accesses when
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* off- and onlining cores wildly.
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*/
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static DEFINE_MUTEX(x86_cpu_hotplug_driver_mutex);
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void cpu_hotplug_driver_lock()
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{
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mutex_lock(&x86_cpu_hotplug_driver_mutex);
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}
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void cpu_hotplug_driver_unlock()
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{
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mutex_unlock(&x86_cpu_hotplug_driver_mutex);
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}
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ssize_t arch_cpu_probe(const char *buf, size_t count) { return -1; }
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ssize_t arch_cpu_release(const char *buf, size_t count) { return -1; }
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#else
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#else
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static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
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static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
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#define get_idle_for_cpu(x) (idle_thread_array[(x)])
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#define get_idle_for_cpu(x) (idle_thread_array[(x)])
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