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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/cris
parentede3d0fba99520f268067917b50858d788bc41da (diff)
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[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/cris')
-rw-r--r--arch/cris/arch-v32/kernel/smp.c1
-rw-r--r--arch/cris/kernel/process.c2
2 files changed, 3 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/kernel/smp.c b/arch/cris/arch-v32/kernel/smp.c
index 957f551ba5c..13867f4fad1 100644
--- a/arch/cris/arch-v32/kernel/smp.c
+++ b/arch/cris/arch-v32/kernel/smp.c
@@ -161,6 +161,7 @@ void __init smp_callin(void)
REG_WR(intr_vect, irq_regs[cpu], rw_mask, vect_mask);
unmask_irq(IPI_INTR_VECT);
unmask_irq(TIMER_INTR_VECT);
+ preempt_disable();
local_irq_enable();
cpu_set(cpu, cpu_online_map);
diff --git a/arch/cris/kernel/process.c b/arch/cris/kernel/process.c
index 949a0e40e03..7c80afb1046 100644
--- a/arch/cris/kernel/process.c
+++ b/arch/cris/kernel/process.c
@@ -218,7 +218,9 @@ void cpu_idle (void)
idle = default_idle;
idle();
}
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}