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

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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>
This commit is contained in:
Greg Ungerer 2005-06-03 11:35:20 +10:00 committed by Linus Torvalds
parent f4d340cf86
commit b05a720b37
1 changed files with 12 additions and 5 deletions
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17
arch/m68knommu/kernel/process.c
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@ -45,11 +45,13 @@ asmlinkage void ret_from_fork(void);
*/
void default_idle(void)
{
while(1) {
if (need_resched())
__asm__("stop #0x2000" : : : "cc");
schedule();
local_irq_disable();
while (!need_resched()) {
/* This stop will re-enable interrupts */
__asm__("stop #0x2000" : : : "cc");
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 */
idle();
while (1) {
idle();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
void machine_restart(char * __unused)