[PATCH] stop_cpu() needs to use raw_smp_processor_id()

From: Ananth N Mavinakayanahalli
Date: Tue Jun 16 2009 - 07:19:54 EST

With DEBUG_PREEMPT on, on an s390 box, we are seeing:

BUG: using smp_processor_id() in preemptible [00000000] code: insmod/3006
caller is arch_arm_kprobe+0x2c/0x90
CPU: 0 Not tainted 2.6.30-rc8-tipjun10-02053-g39ae214 #7
Process insmod (pid: 3006, task: 000000007df31410, ksp: 000000007e087a28)
0000000000000000 000000007e087c38 0000000000000002 0000000000000000
000000007e087cd8 000000007e087c50 000000007e087c50 0000000000048156
00000000003e4de8 000000000002b830 0000000000000000 0000000000000000
0000000000000000 000000007e087c38 ffffffff0000000d 000000007e087ca8
000000000040a780 000000000001635c 000000007e087c38 000000007e087c80
Call Trace:
([<00000000000162e6>] show_trace+0x13a/0x148)
[<00000000001f123a>] debug_smp_processor_id+0x136/0x13c
[<00000000003ddbd8>] arch_arm_kprobe+0x2c/0x90
[<00000000003df8cc>] register_kprobe+0x630/0x684
[<000003e000241056>] kprobe_init+0x56/0xa8 [kprobe_example]
[<00000000000120c2>] do_one_initcall+0x3e/0x16c
[<000000000007cb4c>] SyS_init_module+0xc4/0x1fc
[<0000000000027f42>] sysc_noemu+0x10/0x16
[<0000004a4493324e>] 0x4a4493324e

Digging further this seems to be due to stop_cpu().

Shouldn't stop_cpu() be using raw_smp_processor_id()?

Signed-off-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
kernel/stop_machine.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.30/kernel/stop_machine.c
--- linux-2.6.30.orig/kernel/stop_machine.c
+++ linux-2.6.30/kernel/stop_machine.c
@@ -68,7 +68,7 @@ static void stop_cpu(struct work_struct
enum stopmachine_state curstate = STOPMACHINE_NONE;
struct stop_machine_data *smdata = &idle;
- int cpu = smp_processor_id();
+ int cpu = raw_smp_processor_id();
int err;

if (!active_cpus) {
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