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Message-Id: <20090306052354.171EEDDF4E@ozlabs.org>
Date: Thu, 05 Mar 2009 17:27:23 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: Ingo Molnar <mingo@...hat.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 5/10] cpumask: avoid playing with cpus_allowed in speedstep-ich.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).
For speedstep_set_state and speedstep_get_state we use
smp_call_function_single: this had the advantage of being more
efficient, too.
For speedstep_get_freqs() in speedstep_cpu_init(), we use
work_on_cpu: slightly less efficient, but not performance critical.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
arch/x86/kernel/cpu/cpufreq/speedstep-ich.c | 79 +++++++++++++++-------------
arch/x86/kernel/cpu/cpufreq/speedstep-lib.c | 2
2 files changed, 44 insertions(+), 37 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
@@ -88,7 +88,8 @@ 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)
{
@@ -142,6 +143,11 @@ static void speedstep_set_state (unsigne
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
@@ -229,22 +235,28 @@ 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_processor_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_processor_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;
}
/**
@@ -259,15 +271,15 @@ static int speedstep_target (struct cpuf
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;
@@ -277,20 +289,13 @@ static int speedstep_target (struct cpuf
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;
@@ -313,33 +318,35 @@ static int speedstep_verify (struct cpuf
return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
}
+static long get_freqs_on_cpu(void *_policy)
+{
+ struct cpufreq_policy *policy = _policy;
+
+ return speedstep_get_freqs(speedstep_processor,
+ &speedstep_freqs[SPEEDSTEP_LOW].frequency,
+ &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
+ &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;
/* only run on CPU to be set, or on its sibling */
#ifdef CONFIG_SMP
cpumask_copy(policy->cpus, &per_cpu(cpu_sibling_map, 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);
+ result = work_on_cpu(policy_cpu, get_freqs_on_cpu, policy);
if (result)
return result;
/* 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
@@ -205,7 +205,7 @@ static unsigned int pentium4_get_frequen
return (fsb * mult);
}
-
+/* Warning: may get called from smp_call_function_single. */
unsigned int speedstep_get_processor_frequency(unsigned int processor)
{
switch (processor) {
--
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