@@ -3576,18 +3576,17 @@ static int __devinit workqueue_cpu_down_
#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,
- };
-
- 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);
+ struct work_for_cpu wfc = { .fn = fn, .arg = arg };
+
+ 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);
The existing work_on_cpu() implementation is hugely inefficient. It creates a new kthread, execute that single function and then let the kthread die on each invocation. Now that system_wq can handle concurrent executions, there's no advantage of doing this. Reimplement work_on_cpu() using system_wq which makes it simpler and way more efficient. stable: While this isn't a fix in itself, it's needed to fix a workqueue related bug in cpufreq/powernow-k8. AFAICS, this shouldn't break other existing users. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Len Brown <lenb@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@vger.kernel.org --- So, here are the two patches which can be applied to 3.6-rc6. I'll post a combined patch to the bugzilla so that Duncan can test it. The only worrying thing is that this might affect the existing work_on_cpu() users in some crazy subtle way. I can't see how it would break anything but it's when I think like that when something bites me. That said, pci-driver is probably the most common use case and it seems to work fine here. Thanks. kernel/workqueue.c | 27 +++++++++------------------ 1 file changed, 9 insertions(+), 18 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html