Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763582AbZFKXAc (ORCPT ); Thu, 11 Jun 2009 19:00:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761986AbZFKW73 (ORCPT ); Thu, 11 Jun 2009 18:59:29 -0400 Received: from ozlabs.org ([203.10.76.45]:37881 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760614AbZFKW70 (ORCPT ); Thu, 11 Jun 2009 18:59:26 -0400 CC: linux-kernel@vger.kernel.org To: davej@redhat.com To: cpufreq@vger.kernel.org CC: Ingo Molnar From: Rusty Russell Date: Thu, 11 Jun 2009 22:59:58 +0930 Subject: [PATCH 2/6] cpumask: avoid playing with cpus_allowed in speedstep-ich.c Cc: Dominik Brodowski Message-Id: <20090611225927.E324ADDD04@ozlabs.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6246 Lines: 202 Impact: don't play with current's cpumask It's generally a very bad idea to mug some process's cpumask: it could legitimately and reasonably be changed by root, which could break us (if done before our code) or them (if we restore the wrong value). We use smp_call_function_single: this had the advantage of being more efficient, too. Signed-off-by: Rusty Russell To: davej@redhat.com To: cpufreq@vger.kernel.org Cc: Dominik Brodowski --- arch/x86/kernel/cpu/cpufreq/speedstep-ich.c | 91 ++++++++++++++++------------ arch/x86/kernel/cpu/cpufreq/speedstep-lib.c | 1 2 files changed, 54 insertions(+), 38 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/speedstep-ich.c b/arch/x86/kernel/cpu/cpufreq/speedstep-ich.c --- a/arch/x86/kernel/cpu/cpufreq/speedstep-ich.c +++ b/arch/x86/kernel/cpu/cpufreq/speedstep-ich.c @@ -89,7 +89,8 @@ static int speedstep_find_register(void) * speedstep_set_state - set the SpeedStep state * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH) * - * Tries to change the SpeedStep state. + * Tries to change the SpeedStep state. Can be called from + * smp_call_function_single. */ static void speedstep_set_state(unsigned int state) { @@ -143,6 +144,11 @@ static void speedstep_set_state(unsigned return; } +/* Wrapper for smp_call_function_single. */ +static void _speedstep_set_state(void *_state) +{ + speedstep_set_state(*(unsigned int *)_state); +} /** * speedstep_activate - activate SpeedStep control in the chipset @@ -226,22 +232,28 @@ static unsigned int speedstep_detect_chi return 0; } -static unsigned int _speedstep_get(const struct cpumask *cpus) +struct get_freq_data { + unsigned int speed; + unsigned int processor; +}; + +static void get_freq_data(void *_data) { - unsigned int speed; - cpumask_t cpus_allowed; + struct get_freq_data *data = _data; - cpus_allowed = current->cpus_allowed; - set_cpus_allowed_ptr(current, cpus); - speed = speedstep_get_frequency(speedstep_processor); - set_cpus_allowed_ptr(current, &cpus_allowed); - dprintk("detected %u kHz as current frequency\n", speed); - return speed; + data->speed = speedstep_get_frequency(data->processor); } static unsigned int speedstep_get(unsigned int cpu) { - return _speedstep_get(cpumask_of(cpu)); + struct get_freq_data data = { .processor = cpu }; + + /* You're supposed to ensure CPU is online. */ + if (smp_call_function_single(cpu, get_freq_data, &data, 1) != 0) + BUG(); + + dprintk("detected %u kHz as current frequency\n", data.speed); + return data.speed; } /** @@ -257,16 +269,16 @@ static int speedstep_target(struct cpufr unsigned int target_freq, unsigned int relation) { - unsigned int newstate = 0; + unsigned int newstate = 0, policy_cpu; struct cpufreq_freqs freqs; - cpumask_t cpus_allowed; int i; if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0], target_freq, relation, &newstate)) return -EINVAL; - freqs.old = _speedstep_get(policy->cpus); + policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask); + freqs.old = speedstep_get(policy_cpu); freqs.new = speedstep_freqs[newstate].frequency; freqs.cpu = policy->cpu; @@ -276,20 +288,13 @@ static int speedstep_target(struct cpufr if (freqs.old == freqs.new) return 0; - cpus_allowed = current->cpus_allowed; - for_each_cpu(i, policy->cpus) { freqs.cpu = i; cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); } - /* switch to physical CPU where state is to be changed */ - set_cpus_allowed_ptr(current, policy->cpus); - - speedstep_set_state(newstate); - - /* allow to be run on all CPUs */ - set_cpus_allowed_ptr(current, &cpus_allowed); + smp_call_function_single(policy_cpu, _speedstep_set_state, &newstate, + true); for_each_cpu(i, policy->cpus) { freqs.cpu = i; @@ -312,33 +317,43 @@ static int speedstep_verify(struct cpufr return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]); } +struct get_freqs { + struct cpufreq_policy *policy; + int ret; +}; + +static void get_freqs_on_cpu(void *_get_freqs) +{ + struct get_freqs *get_freqs = _get_freqs; + + get_freqs->ret = + speedstep_get_freqs(speedstep_processor, + &speedstep_freqs[SPEEDSTEP_LOW].frequency, + &speedstep_freqs[SPEEDSTEP_HIGH].frequency, + &get_freqs->policy->cpuinfo.transition_latency, + &speedstep_set_state); +} static int speedstep_cpu_init(struct cpufreq_policy *policy) { - int result = 0; - unsigned int speed; - cpumask_t cpus_allowed; + int result; + unsigned int policy_cpu, speed; + struct get_freqs gf; /* only run on CPU to be set, or on its sibling */ #ifdef CONFIG_SMP cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu)); #endif - - cpus_allowed = current->cpus_allowed; - set_cpus_allowed_ptr(current, policy->cpus); + policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask); /* detect low and high frequency and transition latency */ - result = speedstep_get_freqs(speedstep_processor, - &speedstep_freqs[SPEEDSTEP_LOW].frequency, - &speedstep_freqs[SPEEDSTEP_HIGH].frequency, - &policy->cpuinfo.transition_latency, - &speedstep_set_state); - set_cpus_allowed_ptr(current, &cpus_allowed); - if (result) - return result; + gf.policy = policy; + smp_call_function_single(policy_cpu, get_freqs_on_cpu, &gf, 1); + if (gf.ret) + return gf.ret; /* get current speed setting */ - speed = _speedstep_get(policy->cpus); + speed = speedstep_get(policy_cpu); if (!speed) return -EIO; diff --git a/arch/x86/kernel/cpu/cpufreq/speedstep-lib.c b/arch/x86/kernel/cpu/cpufreq/speedstep-lib.c --- a/arch/x86/kernel/cpu/cpufreq/speedstep-lib.c +++ b/arch/x86/kernel/cpu/cpufreq/speedstep-lib.c @@ -226,6 +226,7 @@ static unsigned int pentium4_get_frequen } +/* Warning: may get called from smp_call_function_single. */ unsigned int speedstep_get_frequency(unsigned int processor) { switch (processor) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/