2021-09-21 02:56:13

by Andrew Halaney

Subject: [PATCH v3 1/3] dyndbg: make dyndbg a known cli param

Right now dyndbg shows up as an unknown parameter if used on boot:

Unknown command line parameters: dyndbg=+p

That's because it is unknown, it doesn't sit in the __param
section, so the processing done to warn users supplying an unknown
parameter doesn't think it is legitimate.

Install a dummy handler to register it. dynamic debug needs to search
the whole command line for modules listed that are currently builtin,
so there's no real work to be done in this callback.

Fixes: 86d1919a4fb0 ("init: print out unknown kernel parameters")
Signed-off-by: Andrew Halaney <[email protected]>
---
lib/dynamic_debug.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index cb5abb42c16a..84c16309cc63 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -761,6 +761,18 @@ static __init int ddebug_setup_query(char *str)

__setup("ddebug_query=", ddebug_setup_query);

+/*
+ * Install a noop handler to make dyndbg look like a normal kernel cli param.
+ * This avoids warnings about dyndbg being an unknown cli param when supplied
+ * by a user.
+ */
+static __init int dyndbg_setup(char *str)
+{
+ return 1;
+}
+
+__setup("dyndbg=", dyndbg_setup);
+
/*
* File_ops->write method for <debugfs>/dynamic_debug/control. Gathers the
* command text from userspace, parses and executes it.
--
2.31.1

2021-09-22 18:26:08

by Jim Cromie

Subject: Re: [PATCH v3 1/3] dyndbg: make dyndbg a known cli param

On Mon, Sep 20, 2021 at 2:55 PM Andrew Halaney <[email protected]> wrote:
>
> Right now dyndbg shows up as an unknown parameter if used on boot:
>
> Unknown command line parameters: dyndbg=+p
>
> That's because it is unknown, it doesn't sit in the __param
> section, so the processing done to warn users supplying an unknown
> parameter doesn't think it is legitimate.
>
> Install a dummy handler to register it. dynamic debug needs to search
> the whole command line for modules listed that are currently builtin,
> so there's no real work to be done in this callback.
>
> Fixes: 86d1919a4fb0 ("init: print out unknown kernel parameters")
> Signed-off-by: Andrew Halaney <[email protected]>


I just validated that this does NOT block or short circuit bare
dyndbg= processing,

[ 0.981166] dyndbg: dyndbg="+fl"
[ 0.981281] dyndbg: query 0: "+fl"
[ 0.981836] dyndbg: split into words: "+fl"
[ 0.982281] dyndbg: op='+'
[ 0.982861] dyndbg: flags=0xc
[ 0.983281] dyndbg: *flagsp=0xc *maskp=0xffffffff
[ 0.984044] dyndbg: parsed: func="" file="" module="" format="" lineno=0-0
[ 0.984298] dyndbg: changed arch/x86/pci/irq.c:1312
[irq]pcibios_fixup_irqs =fl
[ 0.985284] dyndbg: changed arch/x86/pci/irq.c:1259
[irq]pcibios_lookup_irq =fl
[ 0.986281] dyndbg: changed arch/x86/pci/irq.c:1229
[irq]pcibios_lookup_irq =fl

you have my T-B

> ---
> lib/dynamic_debug.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index cb5abb42c16a..84c16309cc63 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -761,6 +761,18 @@ static __init int ddebug_setup_query(char *str)
>
> __setup("ddebug_query=", ddebug_setup_query);
>
> +/*
> + * Install a noop handler to make dyndbg look like a normal kernel cli param.
> + * This avoids warnings about dyndbg being an unknown cli param when supplied
> + * by a user.
> + */
> +static __init int dyndbg_setup(char *str)
> +{
> + return 1;
> +}
> +
> +__setup("dyndbg=", dyndbg_setup);
> +
> /*
> * File_ops->write method for <debugfs>/dynamic_debug/control. Gathers the
> * command text from userspace, parses and executes it.
> --
> 2.31.1
>