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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/ia64/kernel/smpboot.c
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/ia64/kernel/smpboot.c')
-rw-r--r--arch/ia64/kernel/smpboot.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 400a4898712..8f44e7d2df6 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -399,6 +399,7 @@ start_secondary (void *unused)
Dprintk("start_secondary: starting CPU 0x%x\n", hard_smp_processor_id());
efi_map_pal_code();
cpu_init();
+ preempt_disable();
smp_callin();
cpu_idle();