Commit b05a720b authored Jun 03, 2005 by Greg Ungerer Committed by Linus Torvalds Jun 03, 2005

[PATCH] m68knommu: fix scheduling and race problems in idle loop



Re-work the m68knommu specific idle code according to suggestions
from Nick Piggin <nickpiggin@yahoo.com.au>.

A couple of rules that we need to follow:

1. Preempt should now disabled over idle routines. Should only be enabled
to call schedule() then disabled again.

3. When cpu_idle finds (need_resched() == 'true'), it should call schedule().
It should not call schedule() otherwise.

Also fix interrupt locking around the need_resched() and cpu stop state
so that there is no race condition.

Signed-off-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent f4d340cf

arch/m68knommu/kernel/process.c

+12 −5

Original line number	Diff line number	Diff line
		@@ -45,11 +45,13 @@ asmlinkage void ret_from_fork(void);
		*/
		void default_idle(void)
		{
		while(1) {
		if (need_resched())
		local_irq_disable();
		while (!need_resched()) {
		/* This stop will re-enable interrupts */
		__asm__("stop #0x2000" : : : "cc");
		schedule();
		local_irq_disable();
		}
		local_irq_enable();
		}

		void (*idle)(void) = default_idle;
		@@ -63,7 +65,12 @@ void (*idle)(void) = default_idle;
		void cpu_idle(void)
		{
		/* endless idle loop with no priority at all */
		while (1) {
		idle();
		preempt_enable_no_resched();
		schedule();
		preempt_disable();
		}
		}

		void machine_restart(char * __unused)