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authorLi Zhong <zhong@linux.vnet.ibm.com>2013-04-28 11:25:58 +0800
committerIngo Molnar <mingo@kernel.org>2013-04-29 13:17:33 +0200
commit6296ace467c8640317414ba589b124323806f7ce (patch)
tree0bff9b94a366b77ad622f20aa2c85ae435e35e77 /kernel/time
parenta1412ec539e4025831777ef78a1ce427c97bf400 (diff)
downloadlinaro-lsk-6296ace467c8640317414ba589b124323806f7ce.tar.gz
nohz: Protect smp_processor_id() in tick_nohz_task_switch()
I saw following error when testing the latest nohz code on Power: [ 85.295384] BUG: using smp_processor_id() in preemptible [00000000] code: rsyslogd/3493 [ 85.295396] caller is .tick_nohz_task_switch+0x1c/0xb8 [ 85.295402] Call Trace: [ 85.295408] [c0000001fababab0] [c000000000012dc4] .show_stack+0x110/0x25c (unreliable) [ 85.295420] [c0000001fababba0] [c0000000007c4b54] .dump_stack+0x20/0x30 [ 85.295430] [c0000001fababc10] [c00000000044eb74] .debug_smp_processor_id+0xf4/0x124 [ 85.295438] [c0000001fababca0] [c0000000000d7594] .tick_nohz_task_switch+0x1c/0xb8 [ 85.295447] [c0000001fababd20] [c0000000000b9748] .finish_task_switch+0x13c/0x160 [ 85.295455] [c0000001fababdb0] [c0000000000bbe50] .schedule_tail+0x50/0x124 [ 85.295463] [c0000001fababe30] [c000000000009dc8] .ret_from_fork+0x4/0x54 The code below moves the test into local_irq_save/restore section to avoid the above complaint. Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1367119558.6391.34.camel@ThinkPad-T5421.cn.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index da53c8f2beb..1c9f53b2ddb 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -251,14 +251,15 @@ void tick_nohz_task_switch(struct task_struct *tsk)
{
unsigned long flags;
- if (!tick_nohz_full_cpu(smp_processor_id()))
- return;
-
local_irq_save(flags);
+ if (!tick_nohz_full_cpu(smp_processor_id()))
+ goto out;
+
if (tick_nohz_tick_stopped() && !can_stop_full_tick())
tick_nohz_full_kick();
+out:
local_irq_restore(flags);
}