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| author | Borislav Petkov <bp@amd64.org> | 2010-08-19 20:10:29 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-08-19 23:47:43 +0200 |
| commit | d7c53c9e822a4fefa13a0cae76f3190bfd0d5c11 (patch) | |
| tree | 9f4910ad6e95470bb67f504a09b096a4c2822a8d | |
| parent | x86-32: Fix dummy trampoline-related inline stubs (diff) | |
| download | linux-d7c53c9e822a4fefa13a0cae76f3190bfd0d5c11.tar.xz linux-d7c53c9e822a4fefa13a0cae76f3190bfd0d5c11.zip | |
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>
| -rw-r--r-- | arch/x86/Kconfig | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 19 |
2 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a84fc34c8f77..ac7827fc0823 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -245,6 +245,11 @@ config ARCH_HWEIGHT_CFLAGS config KTIME_SCALAR def_bool X86_32 + +config ARCH_CPU_PROBE_RELEASE + def_bool y + depends on HOTPLUG_CPU + source "init/Kconfig" source "kernel/Kconfig.freezer" diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index abf4a86ffc54..8b3bfc4dd708 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -90,6 +90,25 @@ DEFINE_PER_CPU(int, cpu_state) = { 0 }; static DEFINE_PER_CPU(struct task_struct *, idle_thread_array); #define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x)) #define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p)) + +/* + * We need this for trampoline_base protection from concurrent accesses when + * off- and onlining cores wildly. + */ +static DEFINE_MUTEX(x86_cpu_hotplug_driver_mutex); + +void cpu_hotplug_driver_lock() +{ + mutex_lock(&x86_cpu_hotplug_driver_mutex); +} + +void cpu_hotplug_driver_unlock() +{ + mutex_unlock(&x86_cpu_hotplug_driver_mutex); +} + +ssize_t arch_cpu_probe(const char *buf, size_t count) { return -1; } +ssize_t arch_cpu_release(const char *buf, size_t count) { return -1; } #else static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ; #define get_idle_for_cpu(x) (idle_thread_array[(x)]) |