Re: powermac: More powermac backlight fixes

On Sat, 15 Jul 2006 15:09:00 +0200
Michael Hanselmann [off-list ref] wrote:

This patch fixes several problems:
- The legacy backlight value might be set at interrupt time. Introduced
  a worker to prevent it from directly calling the backlight code.
- via-pmu allows the backlight to be grabbed, in which case we need to
  prevent other kernel code from changing the brightness.
- Don't send PMU requests in via-pmu-backlight when the machine is about
  to sleep or waking up.
- More Kconfig fixes.

...

 static void pmac_backlight_key_worker(void *data);
+static void pmac_backlight_set_legacy_worker(void *data);
+
 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
+static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker, NULL);

I see schedule_work()s in there, but no flush_scheduled_work()s or anything
like that.  Generally, this means there are races against rmmod, close(),
etc.

 
+void pmac_backlight_disable()
+{
+	atomic_inc(&kernel_backlight_disabled);
+}
+
+void pmac_backlight_enable()
+{
+	atomic_dec(&kernel_backlight_disabled);
+}
+

So if userspace calls ioctl(PMU_IOC_GRAB_BACKLIGHT) eleven times, eleven
enables are needed?  (Actually, eleven open()/close() sequences, I think).

Methinks you wanted just

	kernel_backlight_disabled = 1;
?