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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-08 21:39:01 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-09 07:56:33 -0800
commit5bfb5d690f36d316a5f3b4f7775fda996faa6b12 (patch)
treeea53f15293d1ddb49c316eb65df85e939a4f6e5e /arch/h8300
parentede3d0fba99520f268067917b50858d788bc41da (diff)
downloadlinux-linaro-stable-5bfb5d690f36d316a5f3b4f7775fda996faa6b12.tar.gz
[PATCH] sched: disable preempt in idle tasks
Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/h8300')
-rw-r--r--arch/h8300/kernel/process.c28
1 files changed, 15 insertions, 13 deletions
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index 27f1fce64ce4..fe21adf3e75e 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -53,22 +53,18 @@ asmlinkage void ret_from_fork(void);
#if !defined(CONFIG_H8300H_SIM) && !defined(CONFIG_H8S_SIM)
void default_idle(void)
{
- while(1) {
- if (!need_resched()) {
- local_irq_enable();
- __asm__("sleep");
- local_irq_disable();
- }
- schedule();
- }
+ local_irq_disable();
+ if (!need_resched()) {
+ local_irq_enable();
+ /* XXX: race here! What if need_resched() gets set now? */
+ __asm__("sleep");
+ } else
+ local_irq_enable();
}
#else
void default_idle(void)
{
- while(1) {
- if (need_resched())
- schedule();
- }
+ cpu_relax();
}
#endif
void (*idle)(void) = default_idle;
@@ -81,7 +77,13 @@ void (*idle)(void) = default_idle;
*/
void cpu_idle(void)
{
- idle();
+ while (1) {
+ while (!need_resched())
+ idle();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
void machine_restart(char * __unused)