Re: [BUG bisected]: apei_hest_parse explosion

[Yinghai Lu]

On Fri, Feb 22, 2013 at 4:30 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> On Friday, February 22, 2013 09:22:15 AM Thomas Gleixner wrote:
>> On Fri, 22 Feb 2013, Rafael J. Wysocki wrote:
>> > On Friday, February 22, 2013 02:40:58 AM Rafael J. Wysocki wrote:
>> > > It looks like the hest_tab memory mapping is unmapped between acpi_hest_init()
>> > > and aer_acpi_firmware_first(), but I have no idea what may be responsible for
>> > > that.
>> > >
>> > > And the only relevant difference between now and before the commit above seems
>> > > to be the change of the acpi_hest_init() ordering (which now is called earlier).
>> >
>> > We actually don't really need to do that thing so early, I think.  It looks like
>> > we only need to make it available early enough for the AER driver to be able to
>> > use it, so I wonder if moving the acpi_hest_init() to a separate
>> > subsys_initcall() will work around the problem.  That is, something like the
>> > patch below.
>>
>> Yes, that makes the machine boot.
>
> Although for a reason I didn't think about.
>
>> > But even if this helps, I will be wanting to understand what's up here.
>>
>> It's very simple. I have "acpi=off" on the command line. With that
>> acpi_hest_init is never called, so hest_disable is not set .....
>
> Well, that explains things (and means that acpi=off doesn't really get much
> test coverage these days).
>
>> Brilliant stuff that.
>
> The appended patch should fix the breakage too, can you please verify?
>
> Rafael
>
>
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Subject: ACPI / APEI: Fix crash in apei_hest_parse() for acpi=off
>
> After commit 92ef2a2 (ACPI: Change the ordering of PCI root bridge
> driver registrarion), acpi_hest_init() is never called for acpi=off
> (acpi_disabled), so hest_disable is not set, but hest_tab is NULL,
> which causes apei_hest_parse() to crash when it is called from
> aer_acpi_firmware_first().
>
> Fix that by making apei_hest_parse() check if hest_tab is not NULL
> in addition to checking hest_disable.  Also remove the now useless
> acpi_disabled check from apei_hest_parse().
>
> Reported-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  drivers/acpi/apei/hest.c |    5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> Index: test/drivers/acpi/apei/hest.c
> ===================================================================
> --- test.orig/drivers/acpi/apei/hest.c
> +++ test/drivers/acpi/apei/hest.c
> @@ -89,7 +89,7 @@ int apei_hest_parse(apei_hest_func_t fun
>         struct acpi_hest_header *hest_hdr;
>         int i, rc, len;
>
> -       if (hest_disable)
> +       if (hest_disable || !hest_tab)
>                 return -EINVAL;
>
>         hest_hdr = (struct acpi_hest_header *)(hest_tab + 1);
> @@ -216,9 +216,6 @@ void __init acpi_hest_init(void)
>                 return;
>         }
>
> -       if (acpi_disabled)
> -               goto err;
> -
>         status = acpi_get_table(ACPI_SIG_HEST, 0,
>                                 (struct acpi_table_header **)&hest_tab);
>         if (status == AE_NOT_FOUND)
>

Acked-by: Yinghai Lu <yinghai@xxxxxxxxxx>
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