From: Greg Ungerer Date: Fri, 3 Jun 2005 01:35:20 +0000 (+1000) Subject: [PATCH] m68knommu: fix scheduling and race problems in idle loop X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b05a720b374ac6af05b2fd4c70bb2c61a9f461ca;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git [PATCH] m68knommu: fix scheduling and race problems in idle loop Re-work the m68knommu specific idle code according to suggestions from Nick Piggin . 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 Signed-off-by: Linus Torvalds --- diff --git a/arch/m68knommu/kernel/process.c b/arch/m68knommu/kernel/process.c index 2b6c9d32b7a..c4a33f265dc 100644 --- a/arch/m68knommu/kernel/process.c +++ b/arch/m68knommu/kernel/process.c @@ -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)