Re: [Xen-devel] [PATCH 1/2] ACPI: intel-idle: Don't register CPU notifier if we are not running.

["Rafael J. Wysocki" <rjw@xxxxxxx>]

On Tuesday, January 15, 2013 05:23:23 PM Konrad Rzeszutek Wilk wrote:
> The 'intel_idle_probe' probes the CPU and sets the CPU notifier.
> But if later on during the module initialization we fail (say
> in cpuidle_register_driver) we stop loading but we neglected
> to unregister the CPU notifier. This means that during CPU
> hotplug events the system will fail:

This really is for Len, but it appears to be obviously correct, so I'll
take it as a v3.8 fix if Len doesn't object.

I suppose we need that in -stable too?

Rafael


> calling  intel_idle_init+0x0/0x326 @ 1
> intel_idle: MWAIT substates: 0x1120
> intel_idle: v0.4 model 0x2A
> intel_idle: lapic_timer_reliable_states 0xffffffff
> intel_idle: intel_idle yielding to none
> initcall intel_idle_init+0x0/0x326 returned -19 after 14 usecs
> 
> ... some time later, offlining and onlining a CPU:
> 
> cpu 3 spinlock event irq 62
> BUG: unable to ] __cpuidle_register_device+0x1c/0x120
> PGD 99b8b067 PUD 99b95067 PMD 0
> Oops: 0000 [#1] SMP
> Modules linked in: xen_evtchn nouveau mxm_wmi wmi radeon ttm i915 fbcon 
> tileblit font atl1c bitblit softcursor drm_kms_helper video xen_blkfront 
> xen_netfront fb_sys_fops sysimgblt sysfillrect syscopyarea xenfs xen_privcmd 
> mperf
> CPU 0
> Pid: 2302, comm: udevd Not tainted 3.8.0-rc3upstream-00249-g09ad159 #1 MSI 
> MS-7680/H61M-P23 (MS-7680)
> RIP: e030:[<ffffffff814d956c>]  [<ffffffff814d956c>] 
> __cpuidle_register_device+0x1c/0x120
> RSP: e02b:ffff88009dacfcb8  EFLAGS: 00010286
> RAX: 0000000000000000 RBX: ffff880105380000 RCX: 000000000000001c
> RDX: 0000000000000000 RSI: 0000000000000055 RDI: ffff880105380000
> RBP: ffff88009dacfce8 R08: ffffffff81a4f048 R09: 0000000000000008
> R10: 0000000000000008 R11: 0000000000000000 R12: ffff880105380000
> R13: 00000000ffffffdd R14: 0000000000000000 R15: ffffffff81a523d0
> FS:  00007f37bd83b7a0(0000) GS:ffff880105200000(0000) knlGS:0000000000000000
> CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000008 CR3: 00000000a09ea000 CR4: 0000000000042660
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process udevd (pid: 2302, threadinfo ffff88009dace000, task ffff88009afb47f0)
> Stack:
>  ffffffff8107f2d0 ffffffff810c2fb7 ffff88009dacfce8 00000000ffffffea
>  ffff880105380000 00000000ffffffdd ffff88009dacfd08 ffffffff814d9882
>  0000000000000003 ffff880105380000 ffff88009dacfd28 ffffffff81340afd
> Call Trace:
>  [<ffffffff8107f2d0>] ? collect_cpu_info_local+0x30/0x30
>  [<ffffffff810c2fb7>] ? __might_sleep+0xe7/0x100
>  [<ffffffff814d9882>] cpuidle_register_device+0x32/0x70
>  [<ffffffff81340afd>] intel_idle_cpu_init+0xad/0x110
>  [<ffffffff81340bc8>] cpu_hotplug_notify+0x68/0x80
>  [<ffffffff8166023d>] notifier_call_chain+0x4d/0x70
>  [<ffffffff810bc369>] __raw_notifier_call_chain+0x9/0x10
>  [<ffffffff81094a4b>] __cpu_notify+0x1b/0x30
>  [<ffffffff81652cf7>] _cpu_up+0x103/0x14b
>  [<ffffffff81652e18>] cpu_up+0xd9/0xec
>  [<ffffffff8164a254>] store_online+0x94/0xd0
>  [<ffffffff814122fb>] dev_attr_store+0x1b/0x20
>  [<ffffffff81216404>] sysfs_write_file+0xf4/0x170
>  [<ffffffff811a1024>] vfs_write+0xb4/0x130
>  [<ffffffff811a17ea>] sys_write+0x5a/0xa0
>  [<ffffffff816643a9>] system_call_fastpath+0x16/0x1b
> Code: 03 18 00 c9 c3 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 ec 30 48 
> 89 5d e8 4c 89 65 f0 48 89 fb 4c 89 6d f8 e8 84 08 00 00 <48> 8b 78 08 49 89 
> c4 e8 f8 7f c1 ff 89 c2 b8 ea ff ff ff 84 d2
> RIP  [<ffffffff814d956c>] __cpuidle_register_device+0x1c/0x120
>  RSP <ffff88009dacfcb8>
> 
> This patch fixes it by moving the CPU notifier registration
> as the last item to be done by the module.
> 
> Cc: stable@xxxxxxxxxxxxxxx # for 3.6 and above
> Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> Cc: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rjw@xxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  drivers/idle/intel_idle.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 4ba384f..2df9414 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -448,8 +448,6 @@ static int intel_idle_probe(void)
>       else
>               on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
>  
> -     register_cpu_notifier(&cpu_hotplug_notifier);
> -
>       pr_debug(PREFIX "v" INTEL_IDLE_VERSION
>               " model 0x%X\n", boot_cpu_data.x86_model);
>  
> @@ -612,6 +610,7 @@ static int __init intel_idle_init(void)
>                       return retval;
>               }
>       }
> +     register_cpu_notifier(&cpu_hotplug_notifier);
>  
>       return 0;
>  }
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

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