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Message-Id: <20090306052354.B327EDDF5F@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 6/10] cpumask: avoid playing with cpus_allowed in powernow-k8.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).
I use work_on_cpu, which is slightly less efficient than the old code,
but the code is complex enough that using smp_call_function_single()
is not trivial.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
arch/x86/kernel/cpu/cpufreq/powernow-k8.c | 108 +++++++++++++++---------------
1 file changed, 55 insertions(+), 53 deletions(-)
diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -483,19 +483,10 @@ static int core_voltage_post_transition(
return 0;
}
-static int check_supported_cpu(unsigned int cpu)
+static long check_supported_cpu(void *unused)
{
- cpumask_t oldmask;
u32 eax, ebx, ecx, edx;
- unsigned int rc = 0;
-
- oldmask = current->cpus_allowed;
- set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
-
- if (smp_processor_id() != cpu) {
- printk(KERN_ERR PFX "limiting to cpu %u failed\n", cpu);
- goto out;
- }
+ unsigned int rc = -ENODEV;
if (current_cpu_data.x86_vendor != X86_VENDOR_AMD)
goto out;
@@ -532,10 +523,9 @@ static int check_supported_cpu(unsigned
goto out;
}
- rc = 1;
+ rc = 0;
out:
- set_cpus_allowed_ptr(current, &oldmask);
return rc;
}
@@ -1047,10 +1037,16 @@ static int transition_frequency_pstate(s
return res;
}
-/* Driver entry point to switch to the target frequency */
-static int powernowk8_target(struct cpufreq_policy *pol, unsigned targfreq, unsigned relation)
+struct target_data {
+ struct cpufreq_policy *pol;
+ unsigned targfreq;
+ unsigned relation;
+};
+
+static long powernowk8_target_on_cpu(void *_tdata)
{
- cpumask_t oldmask;
+ struct target_data *tdata = _tdata;
+ struct cpufreq_policy *pol = tdata->pol;
struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
u32 checkfid;
u32 checkvid;
@@ -1063,22 +1059,13 @@ static int powernowk8_target(struct cpuf
checkfid = data->currfid;
checkvid = data->currvid;
- /* only run on specific CPU from here on */
- oldmask = current->cpus_allowed;
- set_cpus_allowed_ptr(current, &cpumask_of_cpu(pol->cpu));
-
- if (smp_processor_id() != pol->cpu) {
- printk(KERN_ERR PFX "limiting to cpu %u failed\n", pol->cpu);
- goto err_out;
- }
-
if (pending_bit_stuck()) {
printk(KERN_ERR PFX "failing targ, change pending bit set\n");
goto err_out;
}
dprintk("targ: cpu %d, %d kHz, min %d, max %d, relation %d\n",
- pol->cpu, targfreq, pol->min, pol->max, relation);
+ pol->cpu, tdata->targfreq, pol->min, pol->max, tdata->relation);
if (query_current_values_with_pending_wait(data))
goto err_out;
@@ -1094,7 +1081,9 @@ static int powernowk8_target(struct cpuf
}
}
- if (cpufreq_frequency_table_target(pol, data->powernow_table, targfreq, relation, &newstate))
+ if (cpufreq_frequency_table_target(pol, data->powernow_table,
+ tdata->targfreq, tdata->relation,
+ &newstate))
goto err_out;
mutex_lock(&fidvid_mutex);
@@ -1120,8 +1109,17 @@ static int powernowk8_target(struct cpuf
ret = 0;
err_out:
- set_cpus_allowed_ptr(current, &oldmask);
return ret;
+}
+
+/* Driver entry point to switch to the target frequency */
+static int powernowk8_target(struct cpufreq_policy *pol,
+ unsigned targfreq, unsigned relation)
+{
+ struct target_data tdata = { .pol = pol,
+ .targfreq = targfreq,
+ .relation = relation };
+ return work_on_cpu(pol->cpu, powernowk8_target_on_cpu, &tdata);
}
/* Driver entry point to verify the policy and range of frequencies */
@@ -1135,18 +1133,41 @@ static int powernowk8_verify(struct cpuf
return cpufreq_frequency_table_verify(pol, data->powernow_table);
}
+static long __cpuinit powernowk8_cpu_init_on_cpu(void *_data)
+{
+ struct powernow_k8_data *data = _data;
+
+ if (smp_processor_id() != data->cpu) {
+ printk(KERN_ERR PFX "limiting to cpu %u failed\n", data->cpu);
+ return -EIO;
+ }
+
+ if (pending_bit_stuck()) {
+ printk(KERN_ERR PFX "failing init, change pending bit set\n");
+ return -ENODEV;
+ }
+
+ if (query_current_values_with_pending_wait(data))
+ return -ENODEV;
+
+ if (cpu_family == CPU_OPTERON)
+ fidvid_msr_init();
+
+ return 0;
+}
+
/* per CPU init entry point to the driver */
static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
{
struct powernow_k8_data *data;
- cpumask_t oldmask;
int rc;
if (!cpu_online(pol->cpu))
return -ENODEV;
- if (!check_supported_cpu(pol->cpu))
- return -ENODEV;
+ rc = work_on_cpu(pol->cpu, check_supported_cpu, NULL);
+ if (rc != 0)
+ return rc;
data = kzalloc(sizeof(struct powernow_k8_data), GFP_KERNEL);
if (!data) {
@@ -1199,27 +1220,9 @@ static int __cpuinit powernowk8_cpu_init
pol->cpuinfo.transition_latency = get_transition_latency(data);
/* only run on specific CPU from here on */
- oldmask = current->cpus_allowed;
- set_cpus_allowed_ptr(current, &cpumask_of_cpu(pol->cpu));
-
- if (smp_processor_id() != pol->cpu) {
- printk(KERN_ERR PFX "limiting to cpu %u failed\n", pol->cpu);
+ rc = work_on_cpu(data->cpu, powernowk8_cpu_init_on_cpu, data);
+ if (rc != 0)
goto err_out;
- }
-
- if (pending_bit_stuck()) {
- printk(KERN_ERR PFX "failing init, change pending bit set\n");
- goto err_out;
- }
-
- if (query_current_values_with_pending_wait(data))
- goto err_out;
-
- if (cpu_family == CPU_OPTERON)
- fidvid_msr_init();
-
- /* run on any CPU again */
- set_cpus_allowed_ptr(current, &oldmask);
if (cpu_family == CPU_HW_PSTATE)
cpumask_copy(pol->cpus, cpumask_of(pol->cpu));
@@ -1255,7 +1258,6 @@ static int __cpuinit powernowk8_cpu_init
return 0;
err_out:
- set_cpus_allowed_ptr(current, &oldmask);
powernow_k8_cpu_exit_acpi(data);
kfree(data);
@@ -1337,7 +1339,7 @@ static int __cpuinit powernowk8_init(voi
unsigned int i, supported_cpus = 0;
for_each_online_cpu(i) {
- if (check_supported_cpu(i))
+ if (work_on_cpu(i, check_supported_cpu, NULL) == 0)
supported_cpus++;
}
--
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