[PATCH] markers: let marker_debug as module parameter - Kernel

This is a discussion on [PATCH] markers: let marker_debug as module parameter - Kernel ; if we want to enable marker debug output, we have to modify the code and remake/reinstall the kernel in current code. this patch enable marker_debug to be set when kernel start. Signed-off-by: Lai Jiangshan --- diff --git a/kernel/marker.c b/kernel/marker.c index ...

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Thread: [PATCH] markers: let marker_debug as module parameter

  1. [PATCH] markers: let marker_debug as module parameter


    if we want to enable marker debug output, we have to modify
    the code and remake/reinstall the kernel in current code.

    this patch enable marker_debug to be set when kernel start.

    Signed-off-by: Lai Jiangshan
    ---
    diff --git a/kernel/marker.c b/kernel/marker.c
    index 9f76c4a..5d8404f 100644
    --- a/kernel/marker.c
    +++ b/kernel/marker.c
    @@ -28,8 +28,9 @@
    extern struct marker __start___markers[];
    extern struct marker __stop___markers[];

    -/* Set to 1 to enable marker debug output */
    -static const int marker_debug;
    +static int marker_debug;
    +module_param(marker_debug, bool, 0);
    +MODULE_PARM_DESC(marker_debug, "Set to 1 to enable marker debug output");

    /*
    * markers_mutex nests inside module_mutex. Markers mutex protects the builtin


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  2. Re: [PATCH] markers: let marker_debug as module parameter

    * Lai Jiangshan (laijs@cn.fujitsu.com) wrote:
    >
    > if we want to enable marker debug output, we have to modify
    > the code and remake/reinstall the kernel in current code.
    >
    > this patch enable marker_debug to be set when kernel start.
    >


    Given it's only called at probe registration/unregistration and never
    put in the critical path of an executed marker, it makes sense to make
    this a kernel arg debug option. I like this patch

    Acked-by: Mathieu Desnoyers

    > Signed-off-by: Lai Jiangshan
    > ---
    > diff --git a/kernel/marker.c b/kernel/marker.c
    > index 9f76c4a..5d8404f 100644
    > --- a/kernel/marker.c
    > +++ b/kernel/marker.c
    > @@ -28,8 +28,9 @@
    > extern struct marker __start___markers[];
    > extern struct marker __stop___markers[];
    >
    > -/* Set to 1 to enable marker debug output */
    > -static const int marker_debug;
    > +static int marker_debug;
    > +module_param(marker_debug, bool, 0);
    > +MODULE_PARM_DESC(marker_debug, "Set to 1 to enable marker debug output");
    >
    > /*
    > * markers_mutex nests inside module_mutex. Markers mutex protects the builtin
    >
    >


    --
    Mathieu Desnoyers
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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  3. Re: [PATCH] markers: let marker_debug as module parameter


    * Lai Jiangshan wrote:

    > if we want to enable marker debug output, we have to modify
    > the code and remake/reinstall the kernel in current code.
    >
    > this patch enable marker_debug to be set when kernel start.
    >
    > Signed-off-by: Lai Jiangshan
    > ---
    > diff --git a/kernel/marker.c b/kernel/marker.c
    > index 9f76c4a..5d8404f 100644
    > --- a/kernel/marker.c
    > +++ b/kernel/marker.c
    > @@ -28,8 +28,9 @@
    > extern struct marker __start___markers[];
    > extern struct marker __stop___markers[];
    >
    > -/* Set to 1 to enable marker debug output */
    > -static const int marker_debug;
    > +static int marker_debug;
    > +module_param(marker_debug, bool, 0);
    > +MODULE_PARM_DESC(marker_debug, "Set to 1 to enable marker debug output");


    hm, in tip/master we already have ftrace_printk(), which allows such
    debug output to any of the active tracers. That is a far more useful way
    of debugging such things. See:

    http://people.redhat.com/mingo/tip.git/README

    and:

    http://redhat.com/~mingo/sched-devel...dme-tracer.txt

    note how much cleaner and more usable it will also become: no silly
    module flags or recompilation to activate this debug output, and no
    debug clutter in the syslog.

    if you enable tracing in the 'nop' tracer then only the
    ftrace_printk()'s will be printed, no other trace entries.

    Ingo
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