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| author | Kirill Korotaev <dev@sw.ru> | 2005-11-13 16:07:30 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-13 18:14:16 -0800 |
| commit | 4557398f8cbaf9f254cff747534b4724c7f75c4f (patch) | |
| tree | 052b59279b1312a4fde83a76feb4a7a0c5cf7df1 /kernel/stop_machine.c | |
| parent | c5b609797b8e212dbfaf23944da8bf8c53233d5c (diff) | |
| download | lwn-4557398f8cbaf9f254cff747534b4724c7f75c4f.tar.gz lwn-4557398f8cbaf9f254cff747534b4724c7f75c4f.zip | |
[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/stop_machine.c')
| -rw-r--r-- | kernel/stop_machine.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 84a9d18aa8da..b3d4dc858e35 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 |