Commit 49487a3d authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] cpu_idle() startup race fix

Diagnosis from Christian Vogel <vogel@skunk.physik.uni-erlangen.de>

cpu_idle() tests pm_idle() just once then falls into the

	while (!need_resched())
		idle();

loop.

Problem is, that loop never terminates (need_resched() always returns false
on preemptive kernels).

The other problem is that ACPI updates pm_idle _after_ cpu_idle() has taken a
local copy.  So we always call default_idle(), even when pm_idle is pointing
at a new idle handler.

So fix it to pick up changed values of pm_idle() each time around the inner
loop.
parent 1dfe1754
......@@ -138,12 +138,15 @@ void cpu_idle (void)
{
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched()) {
void (*idle)(void) = pm_idle;
if (!idle)
idle = default_idle;
irq_stat[smp_processor_id()].idle_timestamp = jiffies;
while (!need_resched())
idle();
}
schedule();
}
}
......
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