RE: [Xen-devel] [RFC PATCH] acpi/xen: Evaluate the _PDC properly (for 2.6.32, and 2.6.39)

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Konrad Rzeszutek Wilk
> Sent: Wednesday, June 15, 2011 9:46 PM
> 
> I was trying to bring up an prototype box and it while it booted fine under
> Linux, if I tried to do it under Dom0 with a modified Linux kernel it crashed.
> By modified I mean it had the "xen/acpi: add xen acpi processor driver" patch 
> in
> it.
> 
> I traced it down to a one line fix which fixed the issue.
> It might make sense to back-port this to the 2.6.32 tree, and it _might_ fix
> some problems folks had with the processor_xen module (CC-ed here). If you
> see a similar stack trace to the one outlined in the patch - then you might
> be hitting this bug.

this is a bug triggered by rebase. :-)

In 2.6.32:

static int acpi_processor_set_pdc(struct acpi_processor *pr)

In 3.0:

void __cpuinit acpi_processor_set_pdc(acpi_handle handle)

> 
> Anyhow, I am not that familiar with Linux ACPI parser or how the P states
> are exposed - so it might be that this patch is completly bogus. Feedback
> would be much appreciated.

the patch is of course correct in 3.0 context.

Thanks
Kevin

> 
> 
> commit 498adade0091900564e6a6bf06a0f793f09d4764
> Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Date:   Tue Jun 14 21:44:35 2011 -0400
> 
>     acpi/xen: Evaluate the _PDC properly.
> 
>     The call to evaluate the _PDC was passing in the wrong argument.
> 
>     Instead of passing in the acpi_handle it was passing in the structure
>     that held the acpi_handle as the second member. This can cause
>     the wrong evaluation on some machines ending up in trying to evaluate
>     the _PDC and dereferencing the prefix node (which is not part of
>     that structure) and causing a NULL pointer exception.
> 
>     The results after running with this patch (and yes, there are no _PDC
>     on this box):
> 
>     nsxfeval-0180 [2017820672] [4294967276] evaluate_object       :
> ----Entry
>     nsxfeval-0359 [2017820672] [4294967276] evaluate_object       :
> ----Exit- ****Exception****: AE_BAD_PARAMETER
>     processor_core-0306 [2017820672] [4294967275]
> processor_eval_pdc    : Could not evaluate _PDC, using legacy perf. control.
>     nsxfeval-0180 [2017820672] [4294967276] evaluate_object       :
> ----Entry
>     nsxfeval-0263 [2017820672] [4294967276] evaluate_object       :
> pathname is [_PPC]
>       nseval-0090 [2017820672] [4294967277] ns_evaluate           :
> ----Entry
>      nsutils-0707 [2017820672] [4294967278] ns_get_node           :
> ----Entry ffffffff8173d637
>      nsutils-0391 [2017820672] [4294967279] ns_internalize_name   :
> ----Entry
>      nsutils-0280 [2017820672] [4294967280] ns_build_internal_name:
> ----Entry
> 
>     Without the patch (I enabled tracing here so there are more details,
>     note the prefix scope):
> 
>     nsxfeval-0180 [2017820672] [4294967276] evaluate_object       :
> ----Entry
>       utcopy-0641 [2017820672] [4294967277] ut_copy_eobject_to_iob:
> ----Entry
>       utcopy-0459 [2017820672] [4294967278] ut_copy_esimple_to_isi:
> ----Entry
>     utobject-0097 [2017820672] [4294967279] ut_create_internal_obj:
> ----Entry Buffer
>     utobject-0385 [2017820672] [4294967280] ut_allocate_object_des:
> ----Entry
>     utobject-0401 [2017820672] [4294967280] ut_allocate_object_des:
> ffff8800779748b8 Size 48
>     utobject-0403 [2017820672] [4294967280] ut_allocate_object_des:
> ----Exit- ffff8800779748b8
>     utobject-0146 [2017820672] [4294967279] ut_create_internal_obj:
> ----Exit- ffff8800779748b8
>       utcopy-0552 [2017820672] [4294967278] ut_copy_esimple_to_isi:
> ----Exit- AE_OK
>       utcopy-0656 [2017820672] [4294967277] ut_copy_eobject_to_iob:
> ----Exit- AE_OK
>     nsxfeval-0263 [2017820672] [4294967276] evaluate_object       :
> pathname is [_PDC]
>       nseval-0090 [2017820672] [4294967277] ns_evaluate           :
> ----Entry
>      nsutils-0707 [2017820672] [4294967278] ns_get_node           :
> ----Entry ffffffff81733097
>      nsutils-0391 [2017820672] [4294967279] ns_internalize_name   :
> ----Entry
>      nsutils-0280 [2017820672] [4294967280] ns_build_internal_name:
> ----Entry
>      nsutils-0363 [2017820672] [4294967280] ns_build_internal_name:
> Returning [ffff880069151ef0] (rel) "_PDC"
>      nsutils-0366 [2017820672] [4294967280] ns_build_internal_name:
> ----Exit- AE_OK
>      nsutils-0419 [2017820672] [4294967279] ns_internalize_name   :
> ----Exit- AE_OK
>      utmutex-0255 [2017820672] [4294967278] ut_acquire_mutex      :
> Thread 2017820672 attempting to acquire Mutex [ACPI_MTX_Namespace]
>          osl-0973 [2017820672] [4294967278] os_wait_semaphore     :
> Waiting for semaphore[ffff88007f004280|1|65535]
>          osl-0992 [2017820672] [4294967278] os_wait_semaphore     :
> Acquired semaphore[ffff88007f004280|1|65535] utmutex-0263 [2017820672]
> [4294967278] ut_acquire_mutex      : Thread 2017820672 acquired Mutex
> [ACPI_MTX_Namespace]
>     nsaccess-0301 [2017820672] [4294967279] ns_lookup             :
> ----Entry
>      nsutils-0663 [2017820672] [4294967280] ns_opens_scope        :
> ----Entry Untyped
>      nsutils-0673 [2017820672] [4294967280] ns_opens_scope        :
> ----Exit- 0000000000000000
>     nsaccess-0398 [2017820672] [4294967279] ns_lookup             :
> Searching relative to prefix scope [ÿÿÿÿ] (ffff880069163800)
>     nsaccess-0510 [2017820672] [4294967279] ns_lookup             :
> Simple Pathname (1 segment, Flags=2)
>       nsdump-0087 [2017820672] [4294967279] ns_print_pathname     :
> [_PDC]
>     nssearch-0297 [2017820672] [4294967280] ns_search_and_enter   :
> ----Entry
>     nssearch-0102 [2017820672] [4294967281] ns_search_one_scope   :
> ----Entry
>      nsnames-0139 [2017820672] [4294967282] ns_get_external_pathna:
> ----Entry ffff880069163800
>     BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000418
>     IP: [<ffffffff8129266f>] acpi_ns_get_pathname_length+0x1f/0x68
>     .. snip..
>     Pid: 1, comm: swapper Not tainted 2.6.39.1-00221-gbb09547 #1 Intel
> Corporation S2600CP/S2600CP
>     .. snip..
>     Call Trace:
>      [<ffffffff81292905>] acpi_ns_get_external_pathname+0x38/0x137
>      [<ffffffff81290a1f>] acpi_ns_search_one_scope+0x4b/0x1f5
>      [<ffffffff81290cfa>] acpi_ns_search_and_enter+0x131/0x42f
>      [<ffffffff81290310>] acpi_ns_lookup+0x4c8/0x6c9
>      [<ffffffff812933e3>] acpi_ns_get_node+0xe8/0x16e
>      [<ffffffff812920bf>] acpi_ns_evaluate+0x83/0x3b6
>      [<ffffffff812916f7>] acpi_evaluate_object+0x1f9/0x35b
>      [<ffffffff81123d7b>] ? kmem_cache_alloc_trace+0xa0/0xb0
>      [<ffffffff814a4e35>] acpi_processor_set_pdc+0x1cc/0x226
>      [<ffffffff814a5a1e>] xen_acpi_processor_add+0x45c/0x59d
> 
>     Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
> diff --git a/drivers/acpi/processor_xen.c b/drivers/acpi/processor_xen.c
> index 43760f8..db54525 100644
> --- a/drivers/acpi/processor_xen.c
> +++ b/drivers/acpi/processor_xen.c
> @@ -311,7 +311,7 @@ static int __cpuinit xen_acpi_processor_add(struct
> acpi_device *device)
>       }
> 
>       /* _PDC call should be done before doing anything else (if reqd.). */
> -     acpi_processor_set_pdc(pr);
> +     acpi_processor_set_pdc(pr->handle);
> 
>  #ifdef CONFIG_CPU_FREQ
>       xen_acpi_processor_ppc_has_changed(pr);
> 
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