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Subject[RFC] Make dynamic debug infrastructure more flexible
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On Thu, 2020-05-21 at 09:08 -0700, Joe Perches wrote:
> On Thu, 2020-05-21 at 16:28 +0300, Stanimir Varbanov wrote:
> > Here we introduce few debug macros with levels (low, medium and
> > high) and debug macro for firmware. Enabling the particular level
> > will be done by dynamic debug.
>
> I'd rather make the logging level facility generic in
> dynamic debug than prefix all formats with what could
> be non-specific content.
>
> From a long time ago:
>
> https://groups.google.com/forum/#!msg/linux.kernel/VlWbno-ZAFw/k_fFadhNHXcJ

Hey Jason.

I believe there are 6 bits left in the unsigned int
use for the line number and flags in struct _ddebug

Assuming the use of a mechanism like

pr_debug_level(level, fmt, ...)

would you be OK with something like this to enable a
level or bitmask test of dynamic debug logging output?

where the output is controlled by something like

echo 'file <filename> level <n> +p' > <debugfs>/dynamic_debug/control

to enable dynamic debug output only at level <n> or higher
or maybe match a bitmap of <n>

(modulo all the rest of the code necessary to use it?)
---
include/linux/dynamic_debug.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index abcd5fde30eb..616dbb2b5921 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -38,6 +38,8 @@ struct _ddebug {
#define _DPRINTK_FLAGS_DEFAULT 0
#endif
unsigned int flags:8;
+ unsigned int level:5;
+ unsigned int level_is_bitmask:1;
#ifdef CONFIG_JUMP_LABEL
union {
struct static_key_true dd_key_true;

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