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

    * Vegard Nossum <vegard.nossum@gmail.com> wrote:

    > On Fri, Jun 20, 2008 at 11:27 PM, Vegard Nossum <vegard.nossum@gmail.com> wrote:
    > > So I guess this function, pnpbios_init() needs the check as well. In
    > > fact, it has this:
    > >
    > > #ifdef CONFIG_PNPACPI
    > > if (!acpi_disabled && !pnpacpi_disabled) {
    > > pnpbios_disabled = 1;
    > > printk(KERN_INFO "PnPBIOS: Disabled by ACPI PNP\n");
    > > return -ENODEV;
    > > }
    > > #endif /* CONFIG_ACPI */
    > >
    > > ...I guess that should be changed to say if (acpi_disabled ||
    > > pnpacpi_disabled)? Or... I don't understand the purpose of the
    > > original test. But it seems to be there since the beginning of time
    > > (or, well, v2.6.12-rc2).
    >
    > Nope. I found the introduction of the change in the historical git repository:
    >
    > commit 4723ebe898a32262ed49fe677897ccea47e72ff4
    > Author: Adam Belay <ambx1@neo.rr.com>
    > Date: Sun Oct 24 15:07:32 2004 -0400
    >
    > [PNPBIOS] disable if ACPI is active
    >
    > As further ACPI pnp functionaility is implemented it is no longer
    > safe to run ACPI and PNPBIOS concurrently.
    >
    > We therefore take the following approach:
    > - attempt to enable ACPI support
    > - if ACPI fails (blacklist etc.) enable pnpbios support
    > - if ACPI support is not compiled in the kernel enable pnpbios support
    >
    > Signed-off-by: Adam Belay <ambx1@neo.rr.com>
    >
    > and now I understand the purpose of the check; pnpbios does not depend
    > on ACPI; ACPI/pnpacpi is incompatible with pnpbios.

    wow, rather old bug - i guess lockdep made it more visible.

    > Yet it remains a fact that pnpbios will discover devices which then
    > ACPI code uses erroneously. Which means that my original fix for Ingo
    > probably is the right one after all. Should I submit another patch
    > which does the right thing for everything under drivers/acpi/, or can
    > you do it on your own? :-)

    i havent seen the warning reappear with your fix after thousands of
    bootups - so i guess we can consider it fixed.

    Len, please consider the patch below. (it's in tip/out-of-tree)

    Ingo

    ----------------->
    commit acc85833791a5d8f84b8df601afc1cc44568dd18
    Author: Vegard Nossum <vegard.nossum@gmail.com>
    Date: Fri Jun 20 15:56:40 2008 +0200

    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>
    Cc: Len Brown <lenb@kernel.org>
    Cc: Zhao Yakui <yakui.zhao@intel.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Alexey Starikovskiy <astarikovskiy@suse.de>
    Cc: Yinghai Lu <yhlu.kernel@gmail.com>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>

    diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
    index b4d4ce0..c3e1eeb 100644
    --- a/drivers/acpi/glue.c
    +++ b/drivers/acpi/glue.c
    @@ -334,6 +334,9 @@ static int __init acpi_rtc_init(void)
    {
    struct device *dev = get_rtc_dev();

    + if (acpi_disabled)
    + return 0;
    +
    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);
    +
    /* Parameter validation */

    if ((type > ACPI_TYPE_LOCAL_MAX) || (!max_depth) || (!user_function)) {

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