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

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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
This commit is contained in:
Linus Torvalds
2012-09-19 11:00:07 -07:00
parent 925a6f0bf8 6889125b8b
commit c5c473e29c
2 changed files with 42 additions and 46 deletions
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25
kernel/workqueue.c
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@@ -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);