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Date: Mon, 13 Apr 2009 09:30:03 +0930 From: Rusty Russell <rusty@...tcorp.com.au> To: cpufreq@...r.kernel.org Cc: Jeremy Fitzhardinge <jeremy@...p.org> Subject: [PATCH 5/7] cpumask: avoid cpumask games in arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c 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). Use rdmsr_on_cpu and wrmsr_on_cpu instead. Signed-off-by: Rusty Russell <rusty@...tcorp.com.au> To: davej@...hat.com To: cpufreq@...r.kernel.org Cc: Jeremy Fitzhardinge <jeremy@...p.org> --- arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c | 60 ++++++----------------- 1 file changed, 17 insertions(+), 43 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c b/arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c --- a/arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c +++ b/arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c @@ -323,14 +323,8 @@ static unsigned int get_cur_freq(unsigne { unsigned l, h; unsigned clock_freq; - cpumask_t saved_mask; - saved_mask = current->cpus_allowed; - set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu)); - if (smp_processor_id() != cpu) - return 0; - - rdmsr(MSR_IA32_PERF_STATUS, l, h); + rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h); clock_freq = extract_clock(l, cpu, 0); if (unlikely(clock_freq == 0)) { @@ -340,11 +334,9 @@ static unsigned int get_cur_freq(unsigne * P-state transition (like TM2). Get the last freq set * in PERF_CTL. */ - rdmsr(MSR_IA32_PERF_CTL, l, h); + rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h); clock_freq = extract_clock(l, cpu, 1); } - - set_cpus_allowed_ptr(current, &saved_mask); return clock_freq; } @@ -467,15 +459,10 @@ static int centrino_target (struct cpufr struct cpufreq_freqs freqs; int retval = 0; unsigned int j, k, first_cpu, tmp; - cpumask_var_t saved_mask, covered_cpus; + cpumask_var_t covered_cpus; - if (unlikely(!alloc_cpumask_var(&saved_mask, GFP_KERNEL))) + if (unlikely(!alloc_cpumask_var(&covered_cpus, GFP_KERNEL))) return -ENOMEM; - if (unlikely(!alloc_cpumask_var(&covered_cpus, GFP_KERNEL))) { - free_cpumask_var(saved_mask); - return -ENOMEM; - } - cpumask_copy(saved_mask, ¤t->cpus_allowed); if (unlikely(per_cpu(centrino_model, cpu) == NULL)) { retval = -ENODEV; @@ -493,7 +480,7 @@ static int centrino_target (struct cpufr first_cpu = 1; for_each_cpu(j, policy->cpus) { - const struct cpumask *mask; + int good_cpu; /* cpufreq holds the hotplug lock, so we are safe here */ if (!cpu_online(j)) @@ -504,32 +491,30 @@ static int centrino_target (struct cpufr * Make sure we are running on CPU that wants to change freq */ if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) - mask = policy->cpus; + good_cpu = cpumask_any_and(policy->cpus, + cpu_online_mask); else - mask = cpumask_of(j); + good_cpu = j; - set_cpus_allowed_ptr(current, mask); - preempt_disable(); - if (unlikely(!cpu_isset(smp_processor_id(), *mask))) { + if (good_cpu >= nr_cpu_ids) { dprintk("couldn't limit to CPUs in this domain\n"); retval = -EAGAIN; if (first_cpu) { /* We haven't started the transition yet. */ - goto migrate_end; + goto out; } - preempt_enable(); break; } msr = per_cpu(centrino_model, cpu)->op_points[newstate].index; if (first_cpu) { - rdmsr(MSR_IA32_PERF_CTL, oldmsr, h); + rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h); if (msr == (oldmsr & 0xffff)) { dprintk("no change needed - msr was and needs " "to be %x\n", oldmsr); retval = 0; - goto migrate_end; + goto out; } freqs.old = extract_clock(oldmsr, cpu, 0); @@ -553,14 +538,11 @@ static int centrino_target (struct cpufr oldmsr |= msr; } - wrmsr(MSR_IA32_PERF_CTL, oldmsr, h); - if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) { - preempt_enable(); + wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h); + if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) break; - } - cpu_set(j, *covered_cpus); - preempt_enable(); + cpumask_set_cpu(j, covered_cpus); } for_each_cpu(k, policy->cpus) { @@ -578,10 +560,8 @@ static int centrino_target (struct cpufr * Best effort undo.. */ - for_each_cpu_mask_nr(j, *covered_cpus) { - set_cpus_allowed_ptr(current, &cpumask_of_cpu(j)); - wrmsr(MSR_IA32_PERF_CTL, oldmsr, h); - } + for_each_cpu(j, covered_cpus) + wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h); tmp = freqs.new; freqs.new = freqs.old; @@ -593,15 +573,9 @@ static int centrino_target (struct cpufr cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); } } - set_cpus_allowed_ptr(current, saved_mask); retval = 0; - goto out; -migrate_end: - preempt_enable(); - set_cpus_allowed_ptr(current, saved_mask); out: - free_cpumask_var(saved_mask); free_cpumask_var(covered_cpus); return retval; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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