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SubjectRe: [PATCH] ACPI: don't walk tables if ACPI was disabled


On Fri, 20 Jun 2008, Vegard Nossum wrote:

> Hi Ingo,
>
> Can you see if this patch solves your problem? There might be other
> functions that needs this guard as well, though. I wonder if maybe this test
> should just be included at the top of every driver that uses ACPI in some
> way. But I'm pretty sure that this lack of initialization is the root of your
> problem in any case :-)
>
> (By the way, I don't know why this problem popped up at this time, maybe it
> was just bad timing/bad luck... How far back do your AE_BAD_PARAMETER in the
> logs go?)
>
>
> Vegard
>
>
> From: Vegard Nossum <vegard.nossum@gmail.com>
> Date: Fri, 20 Jun 2008 15:39:09 +0200
> Subject: [PATCH] ACPI: don't walk tables if ACPI was disabled
>
> Ingo Molnar wrote:
> > -tip auto-testing started triggering this spinlock corruption message
> > yesterday:
> >
> > [ 3.976213] calling acpi_rtc_init+0x0/0xd3
> > [ 3.980213] ACPI Exception (utmutex-0263): AE_BAD_PARAMETER, Thread F7C50000 could not acquire Mutex [3] [20080321]
> > [ 3.992213] BUG: spinlock bad magic on CPU#0, swapper/1
> > [ 3.992213] lock: c2508dc4, .magic: 00000000, .owner: swapper/1, .owner_cpu: 0
>
> This is apparently because some parts of ACPI, including mutexes, are not
> initialized when acpi=off is passed to the kernel.
>
> Reported-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
> ---
> drivers/acpi/glue.c | 3 +++
> drivers/acpi/namespace/nsxfeval.c | 3 +++
> 2 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
> index 2808dc6..9b227d4 100644
> --- a/drivers/acpi/glue.c
> +++ b/drivers/acpi/glue.c
> @@ -333,6 +333,9 @@ static int __init acpi_rtc_init(void)
> {
> struct device *dev = get_rtc_dev();
>
> + if (acpi_disabled)
> + return 0;
> +

hmm, i would expect dev to be 0 for acpi=off,
since pnp_match would fail, no?

> if (dev) {
> rtc_wake_setup();
> rtc_info.wake_on = rtc_wake_on;
> diff --git a/drivers/acpi/namespace/nsxfeval.c b/drivers/acpi/namespace/nsxfeval.c
> index a8d5491..c274d1d 100644
> --- a/drivers/acpi/namespace/nsxfeval.c
> +++ b/drivers/acpi/namespace/nsxfeval.c
> @@ -391,6 +391,9 @@ acpi_walk_namespace(acpi_object_type type,
>
> ACPI_FUNCTION_TRACE(acpi_walk_namespace);
>
> + if (acpi_disabled)
> + return_ACPI_STATUS(AE_NO_NAMESPACE);
> +

We should probably BUG_ON(acpi_disabled) here,
since it takes a programming bug to hit this case.

-Len

> /* Parameter validation */
>
> if ((type > ACPI_TYPE_LOCAL_MAX) || (!max_depth) || (!user_function)) {
> --
> 1.5.4.1
>
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