On Tue, 2013-08-27 at 17:21 +0800, Gu Zheng wrote:
> Hi Rafael,
>
> On 08/26/2013 11:02 PM, Rafael J. Wysocki wrote:
>
> > On Monday, August 26, 2013 04:43:26 PM Rafael J. Wysocki wrote:
> >> On Monday, August 26, 2013 02:42:09 PM Rafael J. Wysocki wrote:
> >>> On Monday, August 26, 2013 11:13:13 AM Gu Zheng wrote:
> >>>> Hi Rafael,
> >
> > [...]
> >
> >>
> >> OK, so the patch below is quick and dirty and overkill, but it should make the
> >> splat go away at least.
> >
> > And if this patch does make the splat go away for you, please also test the
> > appended one (Tejun, thanks for the hint!).
> >
> > I'll address the ACPI part differently later.
>
> What about changing device_hotplug_lock and acpi_scan_lock to rwsem? like the
> attached one(With a preliminary test, it also can make the splat go away).:)
I am curious how msleep(10) & restart_syscall() work in the change
below. Doesn't the msleep() make s_active held longer time, which can
lead the thread holding device_hotplug_lock to wait it for deletion?
Also, does restart_syscall() release s_active and reopen this file
again?
@@ -408,9 +408,13 @@ static ssize_t show_online(struct device *dev,
struct device_attribute *attr,
{
bool val;
- lock_device_hotplug();
+ if (!read_lock_device_hotplug()) {
+ msleep(10);
+ return restart_syscall();
+ }
+
Thanks,
-Toshi
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