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    SubjectRe: [git pull] sparseirq / irq updates for v2.6.29
    On Sun, Dec 28, 2008 at 3:30 PM, Ingo Molnar <mingo@elte.hu> wrote:
    >
    > * Ingo Molnar <mingo@elte.hu> wrote:
    >
    >> b2e2fe9: sparseirq: work around __weak alias bug
    >
    > here's that fix, standalone too. Kamalesh, i think this should finally fix
    > the crash you are seeing.
    >
    > Ingo
    >
    > ---------------->
    > From b2e2fe99628c4f944c3075258e536197b5a4f3f8 Mon Sep 17 00:00:00 2001
    > From: Ingo Molnar <mingo@elte.hu>
    > Date: Mon, 29 Dec 2008 00:16:45 +0100
    > Subject: [PATCH] sparseirq: work around __weak alias bug
    >
    > Impact: fix boot crash if the kernel is built with certain GCC versions
    >
    > GCC has a bug with __weak alias functions: if the functions are in
    > the same compilation unit as their call site, GCC can decide to
    > inline them - and thus rob the linker of the opportunity to override
    > the weak alias with the real thing.
    >
    > This can lead to the boot crash reported by Kamalesh Babulal:
    >
    > ACPI: Core revision 20080926
    > Setting APIC routing to flat
    > BUG: unable to handle kernel NULL pointer dereference at
    > 0000000000000000
    > IP: [<ffffffff8021f9a8>] add_pin_to_irq_cpu+0x14/0x74
    > PGD 0
    > Oops: 0000 [#1] SMP
    > [...]
    >
    > So move the arch_init_chip_data() function from handle.c to manage.c.
    >
    > Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
    > Signed-off-by: Ingo Molnar <mingo@elte.hu>
    > ---
    > kernel/irq/handle.c | 5 -----
    > kernel/irq/manage.c | 9 +++++++++
    > 2 files changed, 9 insertions(+), 5 deletions(-)
    >

    that is not enough.

    please check

    need one printk, and move two functions into chip.c

    YH
    [PATCH] sparseirq: mvoe two weak functions to chip.c

    Impact: fix panic

    some gcc compiler will remove the weak global blank function
    Linus noted that we could move those function to other unit to workaround it.

    try to workaround it:
    1. one time path: add printk
    2. multi time path: move to chip.c

    Signed-off-by: Yinghai Lu <yinghai@kernel.org>

    diff --git a/init/main.c b/init/main.c
    index d0c5e02..6a7a308 100644
    --- a/init/main.c
    +++ b/init/main.c
    @@ -542,14 +542,11 @@ void __init __weak thread_info_cache_init(void)
    {
    }

    -int __init __weak arch_early_irq_init(void)
    -{
    - return 0;
    -}
    -
    int __init __weak early_irq_init(void)
    {
    - return arch_early_irq_init();
    + printk(KERN_DEBUG "calling __weak early_irq_init()\n");
    +
    + return 0;
    }

    asmlinkage void __init start_kernel(void)
    diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
    index f63c706..2ba0c84 100644
    --- a/kernel/irq/chip.c
    +++ b/kernel/irq/chip.c
    @@ -18,6 +18,16 @@

    #include "internals.h"

    +int __init __weak arch_early_irq_init(void)
    +{
    + return 0;
    +}
    +
    +int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
    +{
    + return 0;
    +}
    +
    /**
    * dynamic_irq_init - initialize a dynamically allocated irq
    * @irq: irq number to initialize
    diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
    index 157c04c..c20db0b 100644
    --- a/kernel/irq/handle.c
    +++ b/kernel/irq/handle.c
    @@ -86,11 +86,6 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
    desc->kstat_irqs = (unsigned int *)ptr;
    }

    -int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
    -{
    - return 0;
    -}
    -
    static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
    {
    memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
    \
     
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      Last update: 2008-12-29 01:03    [W:0.033 / U:121.164 seconds]
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