[PATCH 0/2] DYNAMIC_DEBUG for 5.13

[PATCH 0/2] DYNAMIC_DEBUG for 5.13

[Jim Cromie]

Heres 2 maintenance patches;
- a minor short-circuit optimization
- a cleanup of old cruft

Jim Cromie (2):
  dyndbg: avoid calling dyndbg_emit_prefix when it has no work
  dyndbg: drop uninformative vpr_info

 include/linux/dynamic_debug.h |  9 +++++++++
 lib/dynamic_debug.c           | 10 ++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

-- 
2.30.2

[PATCH 1/2] dyndbg: avoid calling dyndbg_emit_prefix when it has no work

[Jim Cromie]

Wrap function in a static-inline one, which checks flags to avoid
calling the function unnecessarily.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 include/linux/dynamic_debug.h | 9 +++++++++
 lib/dynamic_debug.c           | 9 ++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index a57ee75342cf..173535e725f7 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -32,6 +32,15 @@ struct _ddebug {
 #define _DPRINTK_FLAGS_INCL_FUNCNAME	(1<<2)
 #define _DPRINTK_FLAGS_INCL_LINENO	(1<<3)
 #define _DPRINTK_FLAGS_INCL_TID		(1<<4)
+
+#define _DPRINTK_FLAGS_INCL_ANYSITE		\
+	(_DPRINTK_FLAGS_INCL_MODNAME		\
+	 | _DPRINTK_FLAGS_INCL_FUNCNAME		\
+	 | _DPRINTK_FLAGS_INCL_LINENO)
+#define _DPRINTK_FLAGS_INCL_ANY			\
+	(_DPRINTK_FLAGS_INCL_ANYSITE		\
+	 | _DPRINTK_FLAGS_INCL_TID)
+
 #if defined DEBUG
 #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
 #else
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c70d6347afa2..613293896e47 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -586,7 +586,7 @@ static int remaining(int wrote)
 	return 0;
 }
 
-static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
+static char *__dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 {
 	int pos_after_tid;
 	int pos = 0;
@@ -618,6 +618,13 @@ static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 	return buf;
 }
 
+static inline char *dynamic_emit_prefix(struct _ddebug *desc, char *buf)
+{
+	if (unlikely(desc->flags & _DPRINTK_FLAGS_INCL_ANY))
+		return __dynamic_emit_prefix(desc, buf);
+	return buf;
+}
+
 void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
 {
 	va_list args;
-- 
2.30.2

[PATCH 2/2] dyndbg: drop uninformative vpr_info

[Jim Cromie]

Remove a vpr_info which I added in 2012, when I knew even less than now.
In 2019, a simpler pr_fmt stripped it of context, and any remaining value.

no functional change.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 613293896e47..b260d8218628 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -922,7 +922,6 @@ static const struct seq_operations ddebug_proc_seqops = {
 
 static int ddebug_proc_open(struct inode *inode, struct file *file)
 {
-	vpr_info("called\n");
 	return seq_open_private(file, &ddebug_proc_seqops,
 				sizeof(struct ddebug_iter));
 }
-- 
2.30.2

Re: [PATCH 1/2] dyndbg: avoid calling dyndbg_emit_prefix when it has no work

[Jason Baron]

Hi Jim,

On 4/27/21 9:00 PM, Jim Cromie wrote:
> Wrap function in a static-inline one, which checks flags to avoid
> calling the function unnecessarily.
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  include/linux/dynamic_debug.h | 9 +++++++++
>  lib/dynamic_debug.c           | 9 ++++++++-
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index a57ee75342cf..173535e725f7 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -32,6 +32,15 @@ struct _ddebug {
>  #define _DPRINTK_FLAGS_INCL_FUNCNAME	(1<<2)
>  #define _DPRINTK_FLAGS_INCL_LINENO	(1<<3)
>  #define _DPRINTK_FLAGS_INCL_TID		(1<<4)
> +
> +#define _DPRINTK_FLAGS_INCL_ANYSITE		\
> +	(_DPRINTK_FLAGS_INCL_MODNAME		\
> +	 | _DPRINTK_FLAGS_INCL_FUNCNAME		\
> +	 | _DPRINTK_FLAGS_INCL_LINENO)
> +#define _DPRINTK_FLAGS_INCL_ANY			\
> +	(_DPRINTK_FLAGS_INCL_ANYSITE		\
> +	 | _DPRINTK_FLAGS_INCL_TID)
> +

I'm not sure it's worth having an unused define here by dynamic_debug.c.

I would prefer to just have _DPRINTK_FLAGS_INCL_ANY that has all the flags
in a single define.

>  #if defined DEBUG
>  #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
>  #else
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index c70d6347afa2..613293896e47 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -586,7 +586,7 @@ static int remaining(int wrote)
>  	return 0;
>  }
>  
> -static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
> +static char *__dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
>  {
>  	int pos_after_tid;
>  	int pos = 0;
> @@ -618,6 +618,13 @@ static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
>  	return buf;
>  }
>  
> +static inline char *dynamic_emit_prefix(struct _ddebug *desc, char *buf)
> +{
> +	if (unlikely(desc->flags & _DPRINTK_FLAGS_INCL_ANY))
> +		return __dynamic_emit_prefix(desc, buf);
> +	return buf;
> +}
> +

hmmm - looking at __dynamic_emit_prefix() it starts by doing:


 589 static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
 590 {
 591         int pos_after_tid;
 592         int pos = 0;
 593
 594         *buf = '\0';


So now we are missing the string termination if no flags are set...

Thanks,

-Jason

>  void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
>  {
>  	va_list args;
> 

Re: [PATCH 1/2] dyndbg: avoid calling dyndbg_emit_prefix when it has no work

[jim.cromie]

On Thu, Apr 29, 2021 at 3:03 PM Jason Baron <jbaron@akamai.com> wrote:
>
> Hi Jim,
>
> On 4/27/21 9:00 PM, Jim Cromie wrote:
> > Wrap function in a static-inline one, which checks flags to avoid
> > calling the function unnecessarily.
> >
> > Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> > ---
> >  include/linux/dynamic_debug.h | 9 +++++++++
> >  lib/dynamic_debug.c           | 9 ++++++++-
> >  2 files changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> > index a57ee75342cf..173535e725f7 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -32,6 +32,15 @@ struct _ddebug {
> >  #define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2)
> >  #define _DPRINTK_FLAGS_INCL_LINENO   (1<<3)
> >  #define _DPRINTK_FLAGS_INCL_TID              (1<<4)
> > +
> > +#define _DPRINTK_FLAGS_INCL_ANYSITE          \
> > +     (_DPRINTK_FLAGS_INCL_MODNAME            \
> > +      | _DPRINTK_FLAGS_INCL_FUNCNAME         \
> > +      | _DPRINTK_FLAGS_INCL_LINENO)
> > +#define _DPRINTK_FLAGS_INCL_ANY                      \
> > +     (_DPRINTK_FLAGS_INCL_ANYSITE            \
> > +      | _DPRINTK_FLAGS_INCL_TID)
> > +
>
> I'm not sure it's worth having an unused define here by dynamic_debug.c.
>
> I would prefer to just have _DPRINTK_FLAGS_INCL_ANY that has all the flags
> in a single define.


I have another patch to emit_prefix that uses !ANYSITE to return early
if only TID is wanted
but I can split that out,
or maybe I can pull the other patch forward out of the dd-diet-plan
set Im working.





>
> hmmm - looking at __dynamic_emit_prefix() it starts by doing:
>
>
>  589 static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
>  590 {
>  591         int pos_after_tid;
>  592         int pos = 0;
>  593
>  594         *buf = '\0';
>
>
> So now we are missing the string termination if no flags are set...

yes thats wrong.  looks like I can hoist that init into the caller


> Thanks,
>
> -Jason
>

thanks
Jim