Re: 2.6.13-rc6-rt6

From: Steven Rostedt (rostedt_at_goodmis.org)
Date: 08/16/05

  • Next message: Kyle Moffett: "Re: [PATCH 2.6.13-rc6 1/2] New Syscall: get rlimits of any process"
    To: Ingo Molnar <mingo@elte.hu>
    Date:	Tue, 16 Aug 2005 13:50:47 -0400
    
    

    On Tue, 2005-08-16 at 19:08 +0200, Ingo Molnar wrote:
    > * Ingo Molnar <mingo@elte.hu> wrote:
    >
    > > it's the raw_local_irq_save() in ___trace() that causes trouble.
    >
    > ok, i've uploaded 2.6.13-rc6-rt6, which should fix this. (i've pushed
    > the IRQ tracing into the raw_local_*() primitives, and kept the
    > __raw_local_*() primitives clean, and ___trace() is using them now)
    >
    > Does it boot for you now?

    Ingo,

    I just compiled it and got a bunch of uninitialized variable warnings.
    Are you sure you want this? Here's the problem.

    In something like _trace_cmdline we have:

    static void notrace _trace_cmdline(int cpu, struct cpu_trace *tr)
    {
            unsigned long flags;

            raw_local_save_flags(flags);
            ____trace(cpu, TRACE_CMDLINE, tr, 0, 0, 0, 0, 0, flags);
    }

    Now the raw_local_save_flags is defined as:

    do { typecheck(unsigned long,flags); \
        if (raw_irqs_disabled_flags(flags)) \
            trace_irqs_off(); else trace_irqs_on(); \
            __raw_local_save_flags(flags); } while (0)

    The test of raw_irqs_disabled_flags is checking an uninitialized
    variable. I haven't tried to run it yet since this just doesn't look
    good.

    I changed it for now to the following, but it still desn't make sense to
    me. With a local_save_flags, which doesn't disable or restore the
    interrupts, why bother with the trace at all?

    -- Steve

    Index: linux_realtime_ernie/include/linux/rt_irq.h
    ===================================================================
    --- linux_realtime_ernie/include/linux/rt_irq.h (revision 294)
    +++ linux_realtime_ernie/include/linux/rt_irq.h (working copy)
    @@ -26,7 +26,7 @@
     # endif

     /* soft state does not follow the hard state */
    -# define raw_local_save_flags(flags) do { typecheck(unsigned long,flags); if (raw_irqs_disabled_flags(flags)) trace_irqs_off(); else trace_irqs_on(); __raw_local_save_flags(flags); } while (0)
    +# define raw_local_save_flags(flags) do { typecheck(unsigned long,flags); if (raw_irqs_disabled()) trace_irqs_off(); else trace_irqs_on(); __raw_local_save_flags(flags); } while (0)
     # define raw_local_irq_enable() do { trace_irqs_on(); __raw_local_irq_enable(); } while (0)
     # define raw_local_irq_disable() do { __raw_local_irq_disable(); trace_irqs_off(); } while (0)
     # define raw_local_irq_save(flags) do { __raw_local_irq_save(flags); trace_irqs_off(); } while (0)

    -
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  • Next message: Kyle Moffett: "Re: [PATCH 2.6.13-rc6 1/2] New Syscall: get rlimits of any process"

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