Messages in this thread Patches in this message | | | Date | Wed, 18 Aug 2010 12:11:58 +0300 | From | Sergey Senozhatsky <> | Subject | fix BUG: using smp_processor_id() in preemptible code (resend) |
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Hello,
[ 100.666169] lockdep: fixing up alternatives. [ 100.666183] SMP alternatives: switching to UP code [ 106.942505] BUG: using smp_processor_id() in preemptible [00000000] code: bash/5165 [ 106.942541] caller is thermal_throttle_add_dev+0x20/0xa4 [ 106.942548] Pid: 5165, comm: bash Not tainted 2.6.36-rc1-dbg-git1-00187-g358afc9-dirty #132 [ 106.942553] Call Trace: [ 106.942565] [<ffffffff811f6c01>] debug_smp_processor_id+0xc9/0xe4 [ 106.942571] [<ffffffff8136d377>] thermal_throttle_add_dev+0x20/0xa4 [ 106.942578] [<ffffffff8136d44d>] thermal_throttle_cpu_callback+0x52/0xb5 [ 106.942587] [<ffffffff810573f8>] notifier_call_chain+0x32/0x5e [ 106.942595] [<ffffffff8103c840>] ? cpu_maps_update_begin+0x12/0x14 [ 106.942602] [<ffffffff81057443>] __raw_notifier_call_chain+0x9/0xb [ 106.942609] [<ffffffff8103c703>] __cpu_notify+0x1b/0x2d [ 106.942616] [<ffffffff8136f57d>] _cpu_up+0x6b/0xe9 [ 106.942622] [<ffffffff8136f645>] cpu_up+0x4a/0x57 [ 106.942629] [<ffffffff81363f77>] store_online+0x41/0x6e [ 106.942637] [<ffffffff81291b4f>] sysdev_store+0x1b/0x1d [ 106.942644] [<ffffffff81132186>] sysfs_write_file+0x103/0x13f [ 106.942653] [<ffffffff810db026>] vfs_write+0xb0/0x14f [ 106.942659] [<ffffffff810db2c2>] sys_write+0x45/0x6c [ 106.942668] [<ffffffff81002002>] system_call_fastpath+0x16/0x1b
I have several solutions. Please kindly review. The first one is:
diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index c2a8b26..1269661 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -205,7 +205,9 @@ static int therm_throt_process(bool new_event, int event, int level) static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev) { int err; - struct cpuinfo_x86 *c = &cpu_data(smp_processor_id()); + int cpu = get_cpu(); + struct cpuinfo_x86 *c = &cpu_data(cpu); + put_cpu(); err = sysfs_create_group(&sys_dev->kobj, &thermal_attr_group); if (err)
Should we call smp_processor_id/get_cpu in thermal_throttle_add_dev? We know the cpu when calling thermal_throttle_add_dev (in thermal_throttle_cpu_callback and thermal_throttle_init_device) so we can pass the cpu number when calling it.
My second solution is:
diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index c2a8b26..bcd8499 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -202,11 +202,12 @@ static int therm_throt_process(bool new_event, int event, int level) #ifdef CONFIG_SYSFS /* Add/Remove thermal_throttle interface for CPU device: */ -static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev) +static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev, + unsigned int cpu) { int err; - struct cpuinfo_x86 *c = &cpu_data(smp_processor_id()); - + struct cpuinfo_x86 *c = &cpu_data(cpu); + err = sysfs_create_group(&sys_dev->kobj, &thermal_attr_group); if (err) return err; @@ -251,7 +252,7 @@ thermal_throttle_cpu_callback(struct notifier_block *nfb, case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: mutex_lock(&therm_cpu_lock); - err = thermal_throttle_add_dev(sys_dev); + err = thermal_throttle_add_dev(sys_dev, cpu); mutex_unlock(&therm_cpu_lock); WARN_ON(err); break; @@ -287,7 +288,7 @@ static __init int thermal_throttle_init_device(void) #endif /* connect live CPUs to sysfs */ for_each_online_cpu(cpu) { - err = thermal_throttle_add_dev(get_cpu_sysdev(cpu)); + err = thermal_throttle_add_dev(get_cpu_sysdev(cpu), cpu); WARN_ON(err); } #ifdef CONFIG_HOTPLUG_CPU
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