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From: Kevin Diggs <kevdig@hypersurf.com>
To: linuxppc-dev@ozlabs.org
Subject: to schedule() or not to schedule() ?
Date: Sun, 03 Aug 2008 11:33:15 -0700	[thread overview]
Message-ID: <4895F9EB.8050508@hypersurf.com> (raw)

Hi,


	I have the following near the top of my cpufreq driver target routine:

while(test_and_set_bit(cf750gxmCfgChangeBit,&cf750gxvStateBits)) {
         /*
          * Someone mucking with our cfg? (I hope it is ok to call
          * schedule() here! - truth is I have no idea what I am doing
          * ... my reasoning is I want to yeild the cpu so whoever is
          * mucking around can finish)
          */
         schedule();
}

This is to prevent bad things from happening if someone is trying to 
change a parameter for the driver via sysfs while the target routine is 
running. Fortunately, because I had a bug where this bit was not getting 
cleared on one of the paths through the target routine ... I now know it 
is not safe to call schedule (it got stuck in there - knocked out my adb 
keyboard! - (I think target is called from a timer that the governor 
sets up ... interrupt context?)).

	How does one very briefly yield the cpu in this context?

kevin

             reply	other threads:[~2008-08-03 18:45 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-03 18:33 Kevin Diggs [this message]
2008-08-05 18:37 ` to schedule() or not to schedule() ? Chris Friesen
2008-08-05 19:26   ` Kevin Diggs
2008-08-05 23:00     ` Michael Ellerman
2008-08-06  1:59       ` Kevin Diggs
2008-08-06 21:12         ` Arnd Bergmann

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