Commit c5c473e2 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue / powernow-k8 fix from Tejun Heo:
 "This is the fix for the bug where cpufreq/powernow-k8 was tripping
  BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
  different CPU.

    https://bugzilla.kernel.org/show_bug.cgi?id=47301

  As discussed, the fix is now two parts - one to reimplement
  work_on_cpu() so that it doesn't create a new kthread each time and
  the actual fix which makes powernow-k8 use work_on_cpu() instead of
  performing manual migration.

  While pretty late in the merge cycle, both changes are on the safer
  side.  Jiri and I verified two existing users of work_on_cpu() and
  Duncan confirmed that the powernow-k8 fix survived about 18 hours of
  testing."

* 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
  workqueue: reimplement work_on_cpu() using system_wq
parents 925a6f0b 6889125b
......@@ -35,7 +35,6 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/cpumask.h>
#include <linux/sched.h> /* for current / set_cpus_allowed() */
#include <linux/io.h>
#include <linux/delay.h>
......@@ -1139,16 +1138,23 @@ static int transition_frequency_pstate(struct powernow_k8_data *data,
return res;
}
/* Driver entry point to switch to the target frequency */
static int powernowk8_target(struct cpufreq_policy *pol,
unsigned targfreq, unsigned relation)
struct powernowk8_target_arg {
struct cpufreq_policy *pol;
unsigned targfreq;
unsigned relation;
};
static long powernowk8_target_fn(void *arg)
{
cpumask_var_t oldmask;
struct powernowk8_target_arg *pta = arg;
struct cpufreq_policy *pol = pta->pol;
unsigned targfreq = pta->targfreq;
unsigned relation = pta->relation;
struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
u32 checkfid;
u32 checkvid;
unsigned int newstate;
int ret = -EIO;
int ret;
if (!data)
return -EINVAL;
......@@ -1156,29 +1162,16 @@ static int powernowk8_target(struct cpufreq_policy *pol,
checkfid = data->currfid;
checkvid = data->currvid;
/* only run on specific CPU from here on. */
/* This is poor form: use a workqueue or smp_call_function_single */
if (!alloc_cpumask_var(&oldmask, GFP_KERNEL))
return -ENOMEM;
cpumask_copy(oldmask, tsk_cpus_allowed(current));
set_cpus_allowed_ptr(current, cpumask_of(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;
return -EIO;
}
pr_debug("targ: cpu %d, %d kHz, min %d, max %d, relation %d\n",
pol->cpu, targfreq, pol->min, pol->max, relation);
if (query_current_values_with_pending_wait(data))
goto err_out;
return -EIO;
if (cpu_family != CPU_HW_PSTATE) {
pr_debug("targ: curr fid 0x%x, vid 0x%x\n",
......@@ -1196,7 +1189,7 @@ static int powernowk8_target(struct cpufreq_policy *pol,
if (cpufreq_frequency_table_target(pol, data->powernow_table,
targfreq, relation, &newstate))
goto err_out;
return -EIO;
mutex_lock(&fidvid_mutex);
......@@ -1209,9 +1202,8 @@ static int powernowk8_target(struct cpufreq_policy *pol,
ret = transition_frequency_fidvid(data, newstate);
if (ret) {
printk(KERN_ERR PFX "transition frequency failed\n");
ret = 1;
mutex_unlock(&fidvid_mutex);
goto err_out;
return 1;
}
mutex_unlock(&fidvid_mutex);
......@@ -1220,12 +1212,25 @@ static int powernowk8_target(struct cpufreq_policy *pol,
data->powernow_table[newstate].index);
else
pol->cur = find_khz_freq_from_fid(data->currfid);
ret = 0;
err_out:
set_cpus_allowed_ptr(current, oldmask);
free_cpumask_var(oldmask);
return ret;
return 0;
}
/* Driver entry point to switch to the target frequency */
static int powernowk8_target(struct cpufreq_policy *pol,
unsigned targfreq, unsigned relation)
{
struct powernowk8_target_arg pta = { .pol = pol, .targfreq = targfreq,
.relation = relation };
/*
* Must run on @pol->cpu. cpufreq core is responsible for ensuring
* that we're bound to the current CPU and pol->cpu stays online.
*/
if (smp_processor_id() == pol->cpu)
return powernowk8_target_fn(&pta);
else
return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
}
/* Driver entry point to verify the policy and range of frequencies */
......
......@@ -3576,18 +3576,17 @@ static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb,
#ifdef CONFIG_SMP
struct work_for_cpu {
struct completion completion;
struct work_struct work;
long (*fn)(void *);
void *arg;
long ret;
};
static int do_work_for_cpu(void *_wfc)
static void work_for_cpu_fn(struct work_struct *work)
{
struct work_for_cpu *wfc = _wfc;
struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
wfc->ret = wfc->fn(wfc->arg);
complete(&wfc->completion);
return 0;
}
/**
......@@ -3602,19 +3601,11 @@ static int do_work_for_cpu(void *_wfc)
*/
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
{
struct task_struct *sub_thread;
struct work_for_cpu wfc = {
.completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
.fn = fn,
.arg = arg,
};
struct work_for_cpu wfc = { .fn = fn, .arg = arg };
sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
if (IS_ERR(sub_thread))
return PTR_ERR(sub_thread);
kthread_bind(sub_thread, cpu);
wake_up_process(sub_thread);
wait_for_completion(&wfc.completion);
INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
schedule_work_on(cpu, &wfc.work);
flush_work(&wfc.work);
return wfc.ret;
}
EXPORT_SYMBOL_GPL(work_on_cpu);
......
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