On Friday, August 01, 2014 10:51:46 AM Lan Tianyu wrote:

On 2014年08月01日 05:20, Rafael J. Wysocki wrote:

quoted

On Thursday, July 31, 2014 05:20:26 PM Lan Tianyu wrote:

quoted

The callback of CPU_STARTING event can't sleep and so acpi_cpu_soft_notify()
return directly when CPU_STARTING event is triggered. But cpu hotplug also
happens during S2RAM. The action will become CPU_STARTING_FROZEN. This
patch is to fix missing check the frozen event.

OK

What's the impact of the bug you're fixing?  Do we sleep when we shouldn't?

In particular, are there any bugs reported that are related to it?

quoted

quoted

Signed-off-by: Lan Tianyu <redacted>

There is work to restructure the handling of CPU_TASKS_FROZEN under way
and Chen Gong is driving it.  That's likely to conflict with the last
two patches from you.  Can you please coordinate with Gong?

Hi Rafael:

Thanks for reminder. I just checked Chen Gong's patchset "Gloabl CPU
Hot-plug flag _FROZEN Clean up". There is no conflict between our
patches. Gong's patch is to remove the following macro.

CPU_ONLINE_FROZEN
CPU_UP_PREPARE_FROZEN
CPU_UP_CANCELED_FROZEN
CPU_DOWN_PREPARE_FROZEN
CPU_DOWN_FAILED_FROZEN
CPU_DEAD_FROZEN
CPU_DYING_FROZEN
CPU_STARTING_FROZEN

CPU_TASKS_FROZEN is still available and the CPU events during S2RAM
are still (CPU_xxx | CPU_TASKS_FROZEN).

OK

BTW, this is a bug fix from my opinion and it should be backported to
stable tree.

We'll see.

quoted

quoted

---
 drivers/acpi/processor_driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 4fcbd67..66e2249 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c

@@ -125,7 +125,7 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
 	 * CPU_STARTING and CPU_DYING must not sleep. Return here since
 	 * acpi_bus_get_device() may sleep.
 	 */
-	if (action == CPU_STARTING || action == CPU_DYING)
+	if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING || action == CPU_DYING)
 		return NOTIFY_DONE;
 
 	if (!pr || acpi_bus_get_device(pr->handle, &device))

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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