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authorKirill Korotaev <dev@sw.ru>2005-11-14 00:07:30 (GMT)
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-14 02:14:16 (GMT)
commit4557398f8cbaf9f254cff747534b4724c7f75c4f (patch)
tree052b59279b1312a4fde83a76feb4a7a0c5cf7df1 /kernel
parentc5b609797b8e212dbfaf23944da8bf8c53233d5c (diff)
[PATCH] stop_machine() vs. synchronous IPI send deadlock
This fixes deadlock of stop_machine() vs. synchronous IPI send. The problem is that stop_machine() disables interrupts before disabling preemption on other CPUs. So if another CPU is preempted and then calls something like flush_tlb_all() it will deadlock with CPU doing stop_machine() and which can't process IPI due to disabled IRQs. I changed stop_machine() to do the same things exactly as it does on other CPUs, i.e. it should disable preemption first on _all_ CPUs including itself and only after that disable IRQs. Signed-off-by: Kirill Korotaev <dev@sw.ru> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Andrey Savochkin" <saw@sawoct.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/stop_machine.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 84a9d18..b3d4dc8 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -119,13 +119,12 @@ static int stop_machine(void)
return ret;
}
- /* Don't schedule us away at this point, please. */
- local_irq_disable();
-
/* Now they are all started, make them hold the CPUs, ready. */
+ preempt_disable();
stopmachine_set_state(STOPMACHINE_PREPARE);
/* Make them disable irqs. */
+ local_irq_disable();
stopmachine_set_state(STOPMACHINE_DISABLE_IRQ);
return 0;
@@ -135,6 +134,7 @@ static void restart_machine(void)
{
stopmachine_set_state(STOPMACHINE_EXIT);
local_irq_enable();
+ preempt_enable_no_resched();
}
struct stop_machine_data

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