[PATCH 00/16] dynamic_debug: cleanups, 2 features

[PATCH 00/16] dynamic_debug: cleanups, 2 features

[Jim Cromie]

Patchset starts with 7 "cleanups";
- it changes section name from vague "__verbose" to "__dyndbg"
- cleaner docs, drop obsolete comment & useless debug prints, refine
  verbosity, fix a BUG_ON, ram reporting miscounts.

It adds a few query parsing conveniences;
accept combined file:line & file:func forms

  file inode.c:100-200		# file & line-range
  file inode.c:start_*		# file & function

Then it expands flags:

Adds 'u' user flag, allowing user to compose an arbitrary set of
callsites by marking them with 'u', without altering current
print-modifying flags.

Adds 'PFMLTU' flags, which negate their lower-case counterparts.

Extends flags-spec with filter-flags, which select callsites for
modification based upon their current flags.  This lets user activate
the set of callsites marked with 'u' in a batch.

  echo 'u+p' > control

This was previously submitted before events overtook.
 v1: https://lkml.org/lkml/2019/10/29/989
 v2: https://lkml.org/lkml/2019/11/27/547

Jim Cromie (16):
cleanups:
  dyndbg-docs: eschew file /full/path query in docs
  dyndbg: drop obsolete comment on ddebug_proc_open
  dyndbg: refine debug verbosity
  dyndbg: rename __verbose section to __dyndbg
  dyndbg: fix overcounting of ram used by dyndbg
  dyndbg: fix a BUG_ON in ddebug_describe_flags
  dyndbg: make ddebug_tables list LIFO for add/remove_module
new features:
-parsing conveniences
  dyndbg: refactor parse_linerange out of ddebug_parse_query
  dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'
-flags extensions
--internal rework
  dyndbg: refactor ddebug_read_flags out of ddebug_parse_flags
  dyndbg: combine flags & mask into a struct, use that
  dyndbg: add filter parameter to ddebug_parse_flags
  dyndbg: extend ddebug_parse_flags to accept optional filter-flags
  dyndbg: prefer declarative init in caller, to memset in callee
--expose the features
  dyndbg: add user-flag, negating-flags, and filtering on flags
  dyndbg: allow negating flag-chars in modflags

 .../admin-guide/dynamic-debug-howto.rst       |  75 +++--
 include/asm-generic/vmlinux.lds.h             |   6 +-
 include/linux/dynamic_debug.h                 |   5 +-
 kernel/module.c                               |   2 +-
 lib/dynamic_debug.c                           | 282 ++++++++++--------
 5 files changed, 225 insertions(+), 145 deletions(-)

-- 
2.26.2

[PATCH 01/16] dyndbg-docs: eschew file /full/path query in docs

[Jim Cromie]

Regarding:
commit 2b6783191da7 ("dynamic_debug: add trim_prefix() to provide source-root relative paths")
commit a73619a845d5 ("kbuild: use -fmacro-prefix-map to make __FILE__ a relative path")

2nd commit broke dynamic-debug's "file $fullpath" query form, but
nobody noticed because 1st commit had trimmed prefixes from
control-file output, so the click-copy-pasting of fullpaths into new
queries had ceased; that query form became unused.

Removing the function is cleanest, but it could be useful in
old-compiler corner cases, where __FILE__ still has /full/path,
and it safely does nothing otherwize.

So instead, quietly deprecate "file /full/path" query form, by
removing all /full/paths examples in the docs.  I skipped adding a
back-compat note.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 .../admin-guide/dynamic-debug-howto.rst       | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 0dc2eb8e44e5..2854d418b31b 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -65,10 +65,10 @@ statements via::
 
   nullarbor:~ # cat <debugfs>/dynamic_debug/control
   # filename:lineno [module]function flags format
-  /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:323 [svcxprt_rdma]svc_rdma_cleanup =_ "SVCRDMA Module Removed, deregister RPC RDMA transport\012"
-  /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:341 [svcxprt_rdma]svc_rdma_init =_ "\011max_inline       : %d\012"
-  /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:340 [svcxprt_rdma]svc_rdma_init =_ "\011sq_depth         : %d\012"
-  /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:338 [svcxprt_rdma]svc_rdma_init =_ "\011max_requests     : %d\012"
+  net/sunrpc/svc_rdma.c:323 [svcxprt_rdma]svc_rdma_cleanup =_ "SVCRDMA Module Removed, deregister RPC RDMA transport\012"
+  net/sunrpc/svc_rdma.c:341 [svcxprt_rdma]svc_rdma_init =_ "\011max_inline       : %d\012"
+  net/sunrpc/svc_rdma.c:340 [svcxprt_rdma]svc_rdma_init =_ "\011sq_depth         : %d\012"
+  net/sunrpc/svc_rdma.c:338 [svcxprt_rdma]svc_rdma_init =_ "\011max_requests     : %d\012"
   ...
 
 
@@ -88,7 +88,7 @@ the debug statement callsites with any non-default flags::
 
   nullarbor:~ # awk '$3 != "=_"' <debugfs>/dynamic_debug/control
   # filename:lineno [module]function flags format
-  /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c:1603 [sunrpc]svc_send p "svc_process: st_sendto returned %d\012"
+  net/sunrpc/svcsock.c:1603 [sunrpc]svc_send p "svc_process: st_sendto returned %d\012"
 
 Command Language Reference
 ==========================
@@ -161,13 +161,12 @@ func
 	func svc_tcp_accept
 
 file
-    The given string is compared against either the full pathname, the
-    src-root relative pathname, or the basename of the source file of
-    each callsite.  Examples::
+    The given string is compared against either the src-root relative
+    pathname, or the basename of the source file of each callsite.
+    Examples::
 
 	file svcsock.c
-	file kernel/freezer.c
-	file /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c
+	file kernel/freezer.c	# ie column 1 of control file
 
 module
     The given string is compared against the module name
-- 
2.26.2

[PATCH 02/16] dyndbg: drop obsolete comment on ddebug_proc_open

[Jim Cromie]

commit 4bad78c55002 ("lib/dynamic_debug.c: use seq_open_private() instead of seq_open()")'

The commit was one of a tree-wide set which replaced open-coded
boilerplate with a single tail-call.  It therefore obsoleted the
comment about that boilerplate, clean that up now.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8f199f403ab5..b877774dba96 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -853,13 +853,6 @@ static const struct seq_operations ddebug_proc_seqops = {
 	.stop = ddebug_proc_stop
 };
 
-/*
- * File_ops->open method for <debugfs>/dynamic_debug/control.  Does
- * the seq_file setup dance, and also creates an iterator to walk the
- * _ddebugs.  Note that we create a seq_file always, even for O_WRONLY
- * files where it's not needed, as doing so simplifies the ->release
- * method.
- */
 static int ddebug_proc_open(struct inode *inode, struct file *file)
 {
 	vpr_info("called\n");
-- 
2.26.2

[PATCH 03/16] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty

[Jim Cromie]

The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
voluminous (2 per control file entry + 2 per PAGE).  Moreover, it just
prints pointer and sequence, which is not useful to a dyndbg user.
So just drop them.

Also require verbose>=2 for several other debug printks that are a bit
too chatty for typical needs;

ddebug_change() prints changes, once per modified callsite.  Since
queries like "+p" will enable ~2300 callsites in a typical laptop, a
user probably doesnt need to see them often.  ddebug_exec_queries()
still summarizes with verbose=1.

ddebug_(add|remove)_module() also print 1 line per action on a module,
not needed by typical modprobe user.

This leaves verbose=1 better focussed on the >control parsing process.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index b877774dba96..5900c043e979 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -105,12 +105,15 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
 	return buf;
 }
 
-#define vpr_info(fmt, ...)					\
+#define vnpr_info(lvl, fmt, ...)				\
 do {								\
-	if (verbose)						\
+	if (verbose >= lvl)					\
 		pr_info(fmt, ##__VA_ARGS__);			\
 } while (0)
 
+#define vpr_info(fmt, ...)	vnpr_info(1, fmt, ##__VA_ARGS__)
+#define v2pr_info(fmt, ...)	vnpr_info(2, fmt, ##__VA_ARGS__)
+
 static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 {
 	/* trim any trailing newlines */
@@ -198,7 +201,7 @@ static int ddebug_change(const struct ddebug_query *query,
 				static_branch_enable(&dp->key.dd_key_true);
 #endif
 			dp->flags = newflags;
-			vpr_info("changed %s:%d [%s]%s =%s\n",
+			v2pr_info("changed %s:%d [%s]%s =%s\n",
 				 trim_prefix(dp->filename), dp->lineno,
 				 dt->mod_name, dp->function,
 				 ddebug_describe_flags(dp, flagbuf,
@@ -771,8 +774,6 @@ static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
 	struct _ddebug *dp;
 	int n = *pos;
 
-	vpr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
-
 	mutex_lock(&ddebug_lock);
 
 	if (!n)
@@ -795,9 +796,6 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
 	struct ddebug_iter *iter = m->private;
 	struct _ddebug *dp;
 
-	vpr_info("called m=%p p=%p *pos=%lld\n",
-		 m, p, (unsigned long long)*pos);
-
 	if (p == SEQ_START_TOKEN)
 		dp = ddebug_iter_first(iter);
 	else
@@ -818,8 +816,6 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 	struct _ddebug *dp = p;
 	char flagsbuf[10];
 
-	vpr_info("called m=%p p=%p\n", m, p);
-
 	if (p == SEQ_START_TOKEN) {
 		seq_puts(m,
 			 "# filename:lineno [module]function flags format\n");
@@ -842,7 +838,6 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
  */
 static void ddebug_proc_stop(struct seq_file *m, void *p)
 {
-	vpr_info("called m=%p p=%p\n", m, p);
 	mutex_unlock(&ddebug_lock);
 }
 
@@ -905,7 +900,7 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 	list_add_tail(&dt->link, &ddebug_tables);
 	mutex_unlock(&ddebug_lock);
 
-	vpr_info("%u debug prints in module %s\n", n, dt->mod_name);
+	v2pr_info("%u debug prints in module %s\n", n, dt->mod_name);
 	return 0;
 }
 
@@ -964,7 +959,7 @@ int ddebug_remove_module(const char *mod_name)
 	struct ddebug_table *dt, *nextdt;
 	int ret = -ENOENT;
 
-	vpr_info("removing module \"%s\"\n", mod_name);
+	v2pr_info("removing module \"%s\"\n", mod_name);
 
 	mutex_lock(&ddebug_lock);
 	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
-- 
2.26.2

Re: [PATCH 03/16] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty

[Daniel Thompson]

On Fri, Jun 05, 2020 at 10:26:32AM -0600, Jim Cromie wrote:
> The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
> voluminous (2 per control file entry + 2 per PAGE).  Moreover, it just
> prints pointer and sequence, which is not useful to a dyndbg user.
> So just drop them.

I'd assumed these messages where to help the dyndbg implementer rather
than the dyndbg user. If the verbose messages really are useful to help
users who (mis)configure .../control then should the enable/disable
control be shadowed in debugfs to make it easy to find?


Daniel.

> 
> Also require verbose>=2 for several other debug printks that are a bit
> too chatty for typical needs;
> 
> ddebug_change() prints changes, once per modified callsite.  Since
> queries like "+p" will enable ~2300 callsites in a typical laptop, a
> user probably doesnt need to see them often.  ddebug_exec_queries()
> still summarizes with verbose=1.
> 
> ddebug_(add|remove)_module() also print 1 line per action on a module,
> not needed by typical modprobe user.
> 
> This leaves verbose=1 better focussed on the >control parsing process.
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  lib/dynamic_debug.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index b877774dba96..5900c043e979 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -105,12 +105,15 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
>  	return buf;
>  }
>  
> -#define vpr_info(fmt, ...)					\
> +#define vnpr_info(lvl, fmt, ...)				\
>  do {								\
> -	if (verbose)						\
> +	if (verbose >= lvl)					\
>  		pr_info(fmt, ##__VA_ARGS__);			\
>  } while (0)
>  
> +#define vpr_info(fmt, ...)	vnpr_info(1, fmt, ##__VA_ARGS__)
> +#define v2pr_info(fmt, ...)	vnpr_info(2, fmt, ##__VA_ARGS__)
> +
>  static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>  {
>  	/* trim any trailing newlines */
> @@ -198,7 +201,7 @@ static int ddebug_change(const struct ddebug_query *query,
>  				static_branch_enable(&dp->key.dd_key_true);
>  #endif
>  			dp->flags = newflags;
> -			vpr_info("changed %s:%d [%s]%s =%s\n",
> +			v2pr_info("changed %s:%d [%s]%s =%s\n",
>  				 trim_prefix(dp->filename), dp->lineno,
>  				 dt->mod_name, dp->function,
>  				 ddebug_describe_flags(dp, flagbuf,
> @@ -771,8 +774,6 @@ static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
>  	struct _ddebug *dp;
>  	int n = *pos;
>  
> -	vpr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
> -
>  	mutex_lock(&ddebug_lock);
>  
>  	if (!n)
> @@ -795,9 +796,6 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
>  	struct ddebug_iter *iter = m->private;
>  	struct _ddebug *dp;
>  
> -	vpr_info("called m=%p p=%p *pos=%lld\n",
> -		 m, p, (unsigned long long)*pos);
> -
>  	if (p == SEQ_START_TOKEN)
>  		dp = ddebug_iter_first(iter);
>  	else
> @@ -818,8 +816,6 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
>  	struct _ddebug *dp = p;
>  	char flagsbuf[10];
>  
> -	vpr_info("called m=%p p=%p\n", m, p);
> -
>  	if (p == SEQ_START_TOKEN) {
>  		seq_puts(m,
>  			 "# filename:lineno [module]function flags format\n");
> @@ -842,7 +838,6 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
>   */
>  static void ddebug_proc_stop(struct seq_file *m, void *p)
>  {
> -	vpr_info("called m=%p p=%p\n", m, p);
>  	mutex_unlock(&ddebug_lock);
>  }
>  
> @@ -905,7 +900,7 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
>  	list_add_tail(&dt->link, &ddebug_tables);
>  	mutex_unlock(&ddebug_lock);
>  
> -	vpr_info("%u debug prints in module %s\n", n, dt->mod_name);
> +	v2pr_info("%u debug prints in module %s\n", n, dt->mod_name);
>  	return 0;
>  }
>  
> @@ -964,7 +959,7 @@ int ddebug_remove_module(const char *mod_name)
>  	struct ddebug_table *dt, *nextdt;
>  	int ret = -ENOENT;
>  
> -	vpr_info("removing module \"%s\"\n", mod_name);
> +	v2pr_info("removing module \"%s\"\n", mod_name);
>  
>  	mutex_lock(&ddebug_lock);
>  	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
> -- 
> 2.26.2
> 

Re: [PATCH 03/16] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty

[jim.cromie]

On Mon, Jun 8, 2020 at 5:21 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Fri, Jun 05, 2020 at 10:26:32AM -0600, Jim Cromie wrote:
> > The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
> > voluminous (2 per control file entry + 2 per PAGE).  Moreover, it just
> > prints pointer and sequence, which is not useful to a dyndbg user.
> > So just drop them.
>
> I'd assumed these messages where to help the dyndbg implementer rather
> than the dyndbg user.

So I thought I was guilty of adding those noisy pr_info()s in the
ddebug_proc_* functions,
but I have touched them, changing them to vpr_info().
In any case, I dont think theyre useful to the implementer either.

If the verbose messages really are useful to help
> users who (mis)configure .../control then should the enable/disable
> control be shadowed in debugfs to make it easy to find?
>

I would hesitate to change the API, even if this is just an add-on,
without changes to existing.
OTOH, I could see it added as /proc/dynamic_debug/verbose

with this patch, verbose=1 is better focused on showing the parsing process,
to give user more context as to what his query-command is doing
verbose=2 additionally shows callsites that match the query, including
any unchanged (iirc)

>
> Daniel.
>
> >
> > Also require verbose>=2 for several other debug printks that are a bit
> > too chatty for typical needs;
> >
> > ddebug_change() prints changes, once per modified callsite.  Since
> > queries like "+p" will enable ~2300 callsites in a typical laptop, a
> > user probably doesnt need to see them often.  ddebug_exec_queries()
> > still summarizes with verbose=1.
> >
> > ddebug_(add|remove)_module() also print 1 line per action on a module,
> > not needed by typical modprobe user.
> >
> > This leaves verbose=1 better focussed on the >control parsing process.
> >
> > Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> > ---

Re: [PATCH 03/16] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty

[Daniel Thompson]

On Tue, Jun 09, 2020 at 01:59:41PM -0600, jim.cromie@gmail.com wrote:
> On Mon, Jun 8, 2020 at 5:21 AM Daniel Thompson
> <daniel.thompson@linaro.org> wrote:
> >
> > On Fri, Jun 05, 2020 at 10:26:32AM -0600, Jim Cromie wrote:
> > > The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
> > > voluminous (2 per control file entry + 2 per PAGE).  Moreover, it just
> > > prints pointer and sequence, which is not useful to a dyndbg user.
> > > So just drop them.
> >
> > I'd assumed these messages where to help the dyndbg implementer rather
> > than the dyndbg user.
> 
> So I thought I was guilty of adding those noisy pr_info()s in the
> ddebug_proc_* functions,
> but I have touched them, changing them to vpr_info().
> In any case, I dont think theyre useful to the implementer either.
> 
> If the verbose messages really are useful to help
> > users who (mis)configure .../control then should the enable/disable
> > control be shadowed in debugfs to make it easy to find?
> >
> 
> I would hesitate to change the API, even if this is just an add-on,
> without changes to existing.
> OTOH, I could see it added as /proc/dynamic_debug/verbose

/proc ? 

I was assuming that if the verbose output of dynamic debug is useful to
the person trying to *use* dynamic_debug then it should be in
/sys/kernel/debug/dynamic_debug/verbose .

If they are only likely useful to the person trying to *implement*
dynamic_debug itself (or to check that the infrastructure is not broken)
then there is no reason to add them to debugfs.


> with this patch, verbose=1 is better focused on showing the parsing process,
> to give user more context as to what his query-command is doing
> verbose=2 additionally shows callsites that match the query, including
> any unchanged (iirc)

I'm still a little confused by what benefit having two levels of
verbosity really is. Why does a user need to turn on verbose mode to
figure out what is happening? Why isn't reading back
.../dynamic_debug/control (perhaps using grep and friends) sufficient?


Daniel.

Re: [PATCH 03/16] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty

[jim.cromie]

On Wed, Jun 10, 2020 at 5:16 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Tue, Jun 09, 2020 at 01:59:41PM -0600, jim.cromie@gmail.com wrote:
> > On Mon, Jun 8, 2020 at 5:21 AM Daniel Thompson
> > <daniel.thompson@linaro.org> wrote:
> > >
> > > On Fri, Jun 05, 2020 at 10:26:32AM -0600, Jim Cromie wrote:
> > > > The verbose/debug logging done for `cat $MNT/dynamic_debug/control` is
> > > > voluminous (2 per control file entry + 2 per PAGE).  Moreover, it just
> > > > prints pointer and sequence, which is not useful to a dyndbg user.
> > > > So just drop them.
> > >
> > > I'd assumed these messages where to help the dyndbg implementer rather
> > > than the dyndbg user.
> >
> > So I thought I was guilty of adding those noisy pr_info()s in the
> > ddebug_proc_* functions,
> > but I have touched them, changing them to vpr_info().
> > In any case, I dont think theyre useful to the implementer either.
> >
> > If the verbose messages really are useful to help
> > > users who (mis)configure .../control then should the enable/disable
> > > control be shadowed in debugfs to make it easy to find?
> > >
> >
> > I would hesitate to change the API, even if this is just an add-on,
> > without changes to existing.
> > OTOH, I could see it added as /proc/dynamic_debug/verbose
>
> /proc ?
>
> I was assuming that if the verbose output of dynamic debug is useful to
> the person trying to *use* dynamic_debug then it should be in
> /sys/kernel/debug/dynamic_debug/verbose .

You are correct.
/proc/dynamic_debug/control does exist, so that debugfs isnt required,
but not verbose.  I conflated them while typing.

so, if debugfs isnt present, neither is dynamic_debug/verbose,
and run-time verbosity changes arent possible
but dynamic_debug.verbose=1 still works as boot arg
(I believe, I havent built an non-debugfs kernel myself)

>
> If they are only likely useful to the person trying to *implement*
> dynamic_debug itself (or to check that the infrastructure is not broken)
> then there is no reason to add them to debugfs.
>


>
> > with this patch, verbose=1 is better focused on showing the parsing process,
> > to give user more context as to what his query-command is doing
> > verbose=2 additionally shows callsites that match the query, including
> > any unchanged (iirc)
>
> I'm still a little confused by what benefit having two levels of
> verbosity really is. Why does a user need to turn on verbose mode to
> figure out what is happening? Why isn't reading back
> .../dynamic_debug/control (perhaps using grep and friends) sufficient?
>

verbose=2  prints quite a bit more,
during boot,  290 lines vs 16.
After you see it a dozen times, you dont need it anymore.
but I think its still worth keeping
It also is more chatty about callsites changed by ` echo $querycmd > control `

`cat control` shows complete callsite & flagstate,
it cant also show how commands are processed & changes are applied.


>
> Daniel.

[PATCH 04/16] dyndbg: rename __verbose section to __dyndbg

[Jim Cromie]

dyndbg populates its callsite info into __verbose section, change that
to a more specific and descriptive name, __dyndbg.

Also, per checkpatch:
  simplify __attribute(..) to __section(__dyndbg) declaration.

and 1 spelling fix

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 include/asm-generic/vmlinux.lds.h |  6 +++---
 include/linux/dynamic_debug.h     |  4 ++--
 kernel/module.c                   |  2 +-
 lib/dynamic_debug.c               | 12 ++++++------
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 71e387a5fe90..a117f2757a0d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -320,9 +320,9 @@
 	*(__tracepoints)						\
 	/* implement dynamic printk debug */				\
 	. = ALIGN(8);							\
-	__start___verbose = .;						\
-	KEEP(*(__verbose))                                              \
-	__stop___verbose = .;						\
+	__start___dyndbg = .;						\
+	KEEP(*(__dyndbg))						\
+	__stop___dyndbg = .;						\
 	LIKELY_PROFILE()		       				\
 	BRANCH_PROFILE()						\
 	TRACE_PRINTKS()							\
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 4cf02ecd67de..802480ea8708 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -80,7 +80,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 
 #define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
 	static struct _ddebug  __aligned(8)			\
-	__attribute__((section("__verbose"))) name = {		\
+	__section(__dyndbg) name = {				\
 		.modname = KBUILD_MODNAME,			\
 		.function = __func__,				\
 		.filename = __FILE__,				\
@@ -133,7 +133,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 
 /*
  * "Factory macro" for generating a call to func, guarded by a
- * DYNAMIC_DEBUG_BRANCH. The dynamic debug decriptor will be
+ * DYNAMIC_DEBUG_BRANCH. The dynamic debug descriptor will be
  * initialized using the fmt argument. The function will be called with
  * the address of the descriptor as first argument, followed by all
  * the varargs. Note that fmt is repeated in invocations of this
diff --git a/kernel/module.c b/kernel/module.c
index 646f1e2330d2..c66b18261a6e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3200,7 +3200,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 	if (section_addr(info, "__obsparm"))
 		pr_warn("%s: Ignoring obsolete parameters\n", mod->name);
 
-	info->debug = section_objs(info, "__verbose",
+	info->debug = section_objs(info, "__dyndbg",
 				   sizeof(*info->debug), &info->num_debug);
 
 	return 0;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 5900c043e979..e17d4e2661d8 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -39,8 +39,8 @@
 
 #include <rdma/ib_verbs.h>
 
-extern struct _ddebug __start___verbose[];
-extern struct _ddebug __stop___verbose[];
+extern struct _ddebug __start___dyndbg[];
+extern struct _ddebug __stop___dyndbg[];
 
 struct ddebug_table {
 	struct list_head link;
@@ -1019,14 +1019,14 @@ static int __init dynamic_debug_init(void)
 	int n = 0, entries = 0, modct = 0;
 	int verbose_bytes = 0;
 
-	if (&__start___verbose == &__stop___verbose) {
+	if (&__start___dyndbg == &__stop___dyndbg) {
 		pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
 		return 1;
 	}
-	iter = __start___verbose;
+	iter = __start___dyndbg;
 	modname = iter->modname;
 	iter_start = iter;
-	for (; iter < __stop___verbose; iter++) {
+	for (; iter < __stop___dyndbg; iter++) {
 		entries++;
 		verbose_bytes += strlen(iter->modname) + strlen(iter->function)
 			+ strlen(iter->filename) + strlen(iter->format);
@@ -1049,7 +1049,7 @@ static int __init dynamic_debug_init(void)
 	ddebug_init_success = 1;
 	vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
 		 modct, entries, (int)(modct * sizeof(struct ddebug_table)),
-		 verbose_bytes + (int)(__stop___verbose - __start___verbose));
+		 verbose_bytes + (int)(__stop___dyndbg - __start___dyndbg));
 
 	/* apply ddebug_query boot param, dont unload tables on err */
 	if (ddebug_setup_string[0] != '\0') {
-- 
2.26.2

[PATCH 05/16] dyndbg: fix overcounting of ram used by dyndbg

[Jim Cromie]

during dyndbg init, verbose logging prints its ram overhead.  It
counted strlens of struct _ddebug's 4 string members, in all callsite
entries, which would be approximately correct if each had been
mallocd.  But they are pointers into shared .rodata; for example, all
10 kobject callsites have identical filename, module values.

Its best not to count that memory at all, since we cannot know they
were linked in because of CONFIG_DYNAMIC_DEBUG=y, and we want to
report a number that reflects what ram is saved by deconfiguring it.

Also fix wording and size under-reporting of the __dyndbg section.

Heres my overhead, on a virtme-run VM on a fedora-31 laptop:

  dynamic_debug:dynamic_debug_init: 260 modules, 2479 entries \
    and 10400 bytes in ddebug tables, 138824 bytes in __dyndbg section

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index e17d4e2661d8..25cc1eb86d96 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1017,7 +1017,6 @@ static int __init dynamic_debug_init(void)
 	char *cmdline;
 	int ret = 0;
 	int n = 0, entries = 0, modct = 0;
-	int verbose_bytes = 0;
 
 	if (&__start___dyndbg == &__stop___dyndbg) {
 		pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
@@ -1028,9 +1027,6 @@ static int __init dynamic_debug_init(void)
 	iter_start = iter;
 	for (; iter < __stop___dyndbg; iter++) {
 		entries++;
-		verbose_bytes += strlen(iter->modname) + strlen(iter->function)
-			+ strlen(iter->filename) + strlen(iter->format);
-
 		if (strcmp(modname, iter->modname)) {
 			modct++;
 			ret = ddebug_add_module(iter_start, n, modname);
@@ -1047,9 +1043,9 @@ static int __init dynamic_debug_init(void)
 		goto out_err;
 
 	ddebug_init_success = 1;
-	vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
+	vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in __dyndbg section\n",
 		 modct, entries, (int)(modct * sizeof(struct ddebug_table)),
-		 verbose_bytes + (int)(__stop___dyndbg - __start___dyndbg));
+		 (int)(entries * sizeof(struct _ddebug)));
 
 	/* apply ddebug_query boot param, dont unload tables on err */
 	if (ddebug_setup_string[0] != '\0') {
-- 
2.26.2

[PATCH 06/16] dyndbg: fix a BUG_ON in ddebug_describe_flags

[Jim Cromie]

ddebug_describe_flags currently fills a caller provided string buffer,
after testing its size (also passed) in a BUG_ON.  Fix this by
replacing them with a known-big-enough string buffer wrapped in a
struct, and passing that instead.

Also simplify the flags parameter, and instead de-ref the flags struct
in the caller; this makes the function reusable (soon) where flags are
unpacked.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 25cc1eb86d96..08b8c9c04a17 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -87,22 +87,22 @@ static struct { unsigned flag:8; char opt_char; } opt_array[] = {
 	{ _DPRINTK_FLAGS_NONE, '_' },
 };
 
+struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
+
 /* format a string into buf[] which describes the _ddebug's flags */
-static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
-				    size_t maxlen)
+static char *ddebug_describe_flags(unsigned int flags, struct flagsbuf *fb)
 {
-	char *p = buf;
+	char *p = fb->buf;
 	int i;
 
-	BUG_ON(maxlen < 6);
 	for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
-		if (dp->flags & opt_array[i].flag)
+		if (flags & opt_array[i].flag)
 			*p++ = opt_array[i].opt_char;
-	if (p == buf)
+	if (p == fb->buf)
 		*p++ = '_';
 	*p = '\0';
 
-	return buf;
+	return fb->buf;
 }
 
 #define vnpr_info(lvl, fmt, ...)				\
@@ -141,13 +141,13 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
  * logs the changes.  Takes ddebug_lock.
  */
 static int ddebug_change(const struct ddebug_query *query,
-			unsigned int flags, unsigned int mask)
+			unsigned int pflags, unsigned int mask)
 {
 	int i;
 	struct ddebug_table *dt;
 	unsigned int newflags;
 	unsigned int nfound = 0;
-	char flagbuf[10];
+	struct flagsbuf flags;
 
 	/* search for matching ddebugs */
 	mutex_lock(&ddebug_lock);
@@ -190,22 +190,21 @@ static int ddebug_change(const struct ddebug_query *query,
 
 			nfound++;
 
-			newflags = (dp->flags & mask) | flags;
+			newflags = (dp->flags & mask) | pflags;
 			if (newflags == dp->flags)
 				continue;
 #ifdef CONFIG_JUMP_LABEL
 			if (dp->flags & _DPRINTK_FLAGS_PRINT) {
-				if (!(flags & _DPRINTK_FLAGS_PRINT))
+				if (!(pflags & _DPRINTK_FLAGS_PRINT))
 					static_branch_disable(&dp->key.dd_key_true);
-			} else if (flags & _DPRINTK_FLAGS_PRINT)
+			} else if (pflags & _DPRINTK_FLAGS_PRINT)
 				static_branch_enable(&dp->key.dd_key_true);
 #endif
 			dp->flags = newflags;
 			v2pr_info("changed %s:%d [%s]%s =%s\n",
 				 trim_prefix(dp->filename), dp->lineno,
 				 dt->mod_name, dp->function,
-				 ddebug_describe_flags(dp, flagbuf,
-						       sizeof(flagbuf)));
+				 ddebug_describe_flags(dp->flags, &flags));
 		}
 	}
 	mutex_unlock(&ddebug_lock);
@@ -814,7 +813,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 {
 	struct ddebug_iter *iter = m->private;
 	struct _ddebug *dp = p;
-	char flagsbuf[10];
+	struct flagsbuf flags;
 
 	if (p == SEQ_START_TOKEN) {
 		seq_puts(m,
@@ -825,7 +824,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 	seq_printf(m, "%s:%u [%s]%s =%s \"",
 		   trim_prefix(dp->filename), dp->lineno,
 		   iter->table->mod_name, dp->function,
-		   ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
+		   ddebug_describe_flags(dp->flags, &flags));
 	seq_escape(m, dp->format, "\t\r\n\"");
 	seq_puts(m, "\"\n");
 
-- 
2.26.2

[PATCH 07/16] dyndbg: make ddebug_tables list LIFO for add/remove_module

[Jim Cromie]

loadable modules are the last in on this list, and are the only
modules that could be removed.  ddebug_remove_module() searches from
head, but ddebug_add_module() uses list_add_tail().  Change it to
list_add() for a micro-optimization.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 08b8c9c04a17..494856c04fa7 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -896,7 +896,7 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 	dt->ddebugs = tab;
 
 	mutex_lock(&ddebug_lock);
-	list_add_tail(&dt->link, &ddebug_tables);
+	list_add(&dt->link, &ddebug_tables);
 	mutex_unlock(&ddebug_lock);
 
 	v2pr_info("%u debug prints in module %s\n", n, dt->mod_name);
-- 
2.26.2

[PATCH 08/16] dyndbg: refactor parse_linerange out of ddebug_parse_query

[Jim Cromie]

make the code-block reusable to later handle "file foo.c:101-200" etc.
This should be a 90%+ code-move, with minimal adaptations; reindent,
and scafolding.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 61 +++++++++++++++++++++++++--------------------
 1 file changed, 34 insertions(+), 27 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 494856c04fa7..d43bc3547d3a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -291,6 +291,39 @@ static inline int parse_lineno(const char *str, unsigned int *val)
 	return 0;
 }
 
+static int parse_linerange(struct ddebug_query *query, const char *first)
+{
+	char *last = strchr(first, '-');
+
+	if (query->first_lineno || query->last_lineno) {
+		pr_err("match-spec: line used 2x\n");
+		return -EINVAL;
+	}
+	if (last)
+		*last++ = '\0';
+	if (parse_lineno(first, &query->first_lineno) < 0)
+		return -EINVAL;
+	if (last) {
+		/* range <first>-<last> */
+		if (parse_lineno(last, &query->last_lineno) < 0)
+			return -EINVAL;
+
+		/* special case for last lineno not specified */
+		if (query->last_lineno == 0)
+			query->last_lineno = UINT_MAX;
+
+		if (query->last_lineno < query->first_lineno) {
+			pr_err("last-line:%d < 1st-line:%d\n",
+			       query->last_lineno,
+			       query->first_lineno);
+			return -EINVAL;
+		}
+	} else {
+		query->last_lineno = query->first_lineno;
+	}
+	return 0;
+}
+
 static int check_set(const char **dest, char *src, char *name)
 {
 	int rc = 0;
@@ -349,34 +382,8 @@ static int ddebug_parse_query(char *words[], int nwords,
 							    UNESCAPE_SPECIAL);
 			rc = check_set(&query->format, words[i+1], "format");
 		} else if (!strcmp(words[i], "line")) {
-			char *first = words[i+1];
-			char *last = strchr(first, '-');
-			if (query->first_lineno || query->last_lineno) {
-				pr_err("match-spec: line used 2x\n");
-				return -EINVAL;
-			}
-			if (last)
-				*last++ = '\0';
-			if (parse_lineno(first, &query->first_lineno) < 0)
+			if (parse_linerange(query, words[i+1]))
 				return -EINVAL;
-			if (last) {
-				/* range <first>-<last> */
-				if (parse_lineno(last, &query->last_lineno) < 0)
-					return -EINVAL;
-
-				/* special case for last lineno not specified */
-				if (query->last_lineno == 0)
-					query->last_lineno = UINT_MAX;
-
-				if (query->last_lineno < query->first_lineno) {
-					pr_err("last-line:%d < 1st-line:%d\n",
-						query->last_lineno,
-						query->first_lineno);
-					return -EINVAL;
-				}
-			} else {
-				query->last_lineno = query->first_lineno;
-			}
 		} else {
 			pr_err("unknown keyword \"%s\"\n", words[i]);
 			return -EINVAL;
-- 
2.26.2

[PATCH 09/16] dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'

[Jim Cromie]

Accept these additional query forms:

   echo "file $filestr +_" > control

       path/to/file.c:100	# as from control, column 1
       path/to/file.c:1-100	# or any legal line-range
       path/to/file.c:func_A	# as from an editor/browser
       path/to/file.c:drm_\*	# wildcards still work
       path/to/file.c:*_foo	# lead wildcard too

1st 2 examples are treated as line-ranges, 3,4 are treated as func's

Doc these changes, and sprinkle in a few extra wild-card examples and
trailing # explanation texts.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 .../admin-guide/dynamic-debug-howto.rst       |  5 +++++
 lib/dynamic_debug.c                           | 20 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 2854d418b31b..880d33d1782f 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -159,6 +159,7 @@ func
     of each callsite.  Example::
 
 	func svc_tcp_accept
+	func *recv*		# in rfcomm, bluetooth, ping, tcp
 
 file
     The given string is compared against either the src-root relative
@@ -167,6 +168,9 @@ file
 
 	file svcsock.c
 	file kernel/freezer.c	# ie column 1 of control file
+	file drivers/usb/*	# all callsites under it
+	file inode.c:start_*	# parse :tail as a func (above)
+	file inode.c:1-100	# parse :tail as a line-range (above)
 
 module
     The given string is compared against the module name
@@ -176,6 +180,7 @@ module
 
 	module sunrpc
 	module nfsd
+	module drm*	# both drm, drm_kms_helper
 
 format
     The given string is searched for in the dynamic debug format
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index d43bc3547d3a..8f250c67acbe 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -321,6 +321,8 @@ static int parse_linerange(struct ddebug_query *query, const char *first)
 	} else {
 		query->last_lineno = query->first_lineno;
 	}
+	vpr_info("parsed line %d-%d\n", query->first_lineno,
+		 query->last_lineno);
 	return 0;
 }
 
@@ -357,6 +359,7 @@ static int ddebug_parse_query(char *words[], int nwords,
 {
 	unsigned int i;
 	int rc = 0;
+	char *fline;
 
 	/* check we have an even number of words */
 	if (nwords % 2 != 0) {
@@ -373,7 +376,22 @@ static int ddebug_parse_query(char *words[], int nwords,
 		if (!strcmp(words[i], "func")) {
 			rc = check_set(&query->function, words[i+1], "func");
 		} else if (!strcmp(words[i], "file")) {
-			rc = check_set(&query->filename, words[i+1], "file");
+			if (check_set(&query->filename, words[i+1], "file"))
+				return -EINVAL;
+
+			/* tail :$info is function or line-range */
+			fline = strchr(query->filename, ':');
+			if (!fline)
+				break;
+			*fline++ = '\0';
+			if (isalpha(*fline) || *fline == '*' || *fline == '?') {
+				/* take as function name */
+				if (check_set(&query->function, fline, "func"))
+					return -EINVAL;
+			} else
+				if (parse_linerange(query, fline))
+					return -EINVAL;
+
 		} else if (!strcmp(words[i], "module")) {
 			rc = check_set(&query->module, words[i+1], "module");
 		} else if (!strcmp(words[i], "format")) {
-- 
2.26.2

Re: [PATCH 09/16] dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'

[Jason Baron]

On 6/5/20 12:26 PM, Jim Cromie wrote:
> Accept these additional query forms:
> 
>    echo "file $filestr +_" > control
> 
>        path/to/file.c:100	# as from control, column 1
>        path/to/file.c:1-100	# or any legal line-range
>        path/to/file.c:func_A	# as from an editor/browser
>        path/to/file.c:drm_\*	# wildcards still work
>        path/to/file.c:*_foo	# lead wildcard too
> 
> 1st 2 examples are treated as line-ranges, 3,4 are treated as func's
> 
> Doc these changes, and sprinkle in a few extra wild-card examples and
> trailing # explanation texts.
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  .../admin-guide/dynamic-debug-howto.rst       |  5 +++++
>  lib/dynamic_debug.c                           | 20 ++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
> index 2854d418b31b..880d33d1782f 100644
> --- a/Documentation/admin-guide/dynamic-debug-howto.rst
> +++ b/Documentation/admin-guide/dynamic-debug-howto.rst
> @@ -159,6 +159,7 @@ func
>      of each callsite.  Example::
>  
>  	func svc_tcp_accept
> +	func *recv*		# in rfcomm, bluetooth, ping, tcp
>  
>  file
>      The given string is compared against either the src-root relative
> @@ -167,6 +168,9 @@ file
>  
>  	file svcsock.c
>  	file kernel/freezer.c	# ie column 1 of control file
> +	file drivers/usb/*	# all callsites under it
> +	file inode.c:start_*	# parse :tail as a func (above)
> +	file inode.c:1-100	# parse :tail as a line-range (above)
>  
>  module
>      The given string is compared against the module name
> @@ -176,6 +180,7 @@ module
>  
>  	module sunrpc
>  	module nfsd
> +	module drm*	# both drm, drm_kms_helper
>  
>  format
>      The given string is searched for in the dynamic debug format
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index d43bc3547d3a..8f250c67acbe 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -321,6 +321,8 @@ static int parse_linerange(struct ddebug_query *query, const char *first)
>  	} else {
>  		query->last_lineno = query->first_lineno;
>  	}
> +	vpr_info("parsed line %d-%d\n", query->first_lineno,
> +		 query->last_lineno);
>  	return 0;
>  }
>  
> @@ -357,6 +359,7 @@ static int ddebug_parse_query(char *words[], int nwords,
>  {
>  	unsigned int i;
>  	int rc = 0;
> +	char *fline;
>  
>  	/* check we have an even number of words */
>  	if (nwords % 2 != 0) {
> @@ -373,7 +376,22 @@ static int ddebug_parse_query(char *words[], int nwords,
>  		if (!strcmp(words[i], "func")) {
>  			rc = check_set(&query->function, words[i+1], "func");
>  		} else if (!strcmp(words[i], "file")) {
> -			rc = check_set(&query->filename, words[i+1], "file");
> +			if (check_set(&query->filename, words[i+1], "file"))
> +				return -EINVAL;
> +
> +			/* tail :$info is function or line-range */
> +			fline = strchr(query->filename, ':');
> +			if (!fline)
> +				break;
> +			*fline++ = '\0';
> +			if (isalpha(*fline) || *fline == '*' || *fline == '?') {
> +				/* take as function name */
> +				if (check_set(&query->function, fline, "func"))
> +					return -EINVAL;
> +			} else
> +				if (parse_linerange(query, fline))
> +					return -EINVAL;
> +

coding style here is to use braces for both branches.



>  		} else if (!strcmp(words[i], "module")) {
>  			rc = check_set(&query->module, words[i+1], "module");
>  		} else if (!strcmp(words[i], "format")) {
> 

[PATCH 10/16] dyndbg: refactor ddebug_read_flags out of ddebug_parse_flags

[Jim Cromie]

Currently, ddebug_parse_flags accepts [+-=][pflmt_]+ as flag-spec
strings.  If we allow [pflmt_]*[+-=][pflmt_]+ instead, the (new) 1st
flagset can be used as a filter to select callsites, before applying
changes in the 2nd flagset.  1st step is to split out the flags-reader
so we can use it again.

The point of this is to allow user to compose an arbitrary set of
changes, by marking callsites with [fmlt] flags, and then to
activate that composed set in a single query.

 #> echo '=_' > control			# clear all flags
 #> echo 'module usb* +fmlt' > control	# build the marked set, repeat
 #> echo 'fmlt+p' > control		# activate

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8f250c67acbe..005b8221a9d6 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -413,6 +413,26 @@ static int ddebug_parse_query(char *words[], int nwords,
 	return 0;
 }
 
+static int ddebug_read_flags(const char *str, unsigned int *flags)
+{
+	int i;
+
+	for (; *str ; ++str) {
+		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
+			if (*str == opt_array[i].opt_char) {
+				*flags |= opt_array[i].flag;
+				break;
+			}
+		}
+		if (i < 0) {
+			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
+			return -EINVAL;
+		}
+	}
+	vpr_info("flags=0x%x\n", *flags);
+	return 0;
+}
+
 /*
  * Parse `str' as a flags specification, format [-+=][p]+.
  * Sets up *maskp and *flagsp to be used when changing the
@@ -423,7 +443,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 			       unsigned int *maskp)
 {
 	unsigned flags = 0;
-	int op = '=', i;
+	int op;
 
 	switch (*str) {
 	case '+':
@@ -437,19 +457,8 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 	}
 	vpr_info("op='%c'\n", op);
 
-	for (; *str ; ++str) {
-		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
-			if (*str == opt_array[i].opt_char) {
-				flags |= opt_array[i].flag;
-				break;
-			}
-		}
-		if (i < 0) {
-			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
-			return -EINVAL;
-		}
-	}
-	vpr_info("flags=0x%x\n", flags);
+	if (ddebug_read_flags(str, &flags))
+		return -EINVAL;
 
 	/* calculate final *flagsp, *maskp according to mask and op */
 	switch (op) {
-- 
2.26.2

[PATCH 11/16] dyndbg: combine flags & mask into a struct, use that

[Jim Cromie]

combine flags & mask into a struct, and replace those 2 parameters in
3 functions: ddebug_change, ddebug_parse_flags, ddebug_read_flags,
altering the derefs in them accordingly.

This simplifies the 3 function sigs, preparing for more changes.
We dont yet need mask from ddebug_read_flags, but will soon.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 46 +++++++++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 005b8221a9d6..2ecabfd3f432 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -62,6 +62,11 @@ struct ddebug_iter {
 	unsigned int idx;
 };
 
+struct flagsettings {
+	unsigned int flags;
+	unsigned int mask;
+};
+
 static DEFINE_MUTEX(ddebug_lock);
 static LIST_HEAD(ddebug_tables);
 static int verbose;
@@ -141,7 +146,7 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
  * logs the changes.  Takes ddebug_lock.
  */
 static int ddebug_change(const struct ddebug_query *query,
-			unsigned int pflags, unsigned int mask)
+			 struct flagsettings *mods)
 {
 	int i;
 	struct ddebug_table *dt;
@@ -190,14 +195,14 @@ static int ddebug_change(const struct ddebug_query *query,
 
 			nfound++;
 
-			newflags = (dp->flags & mask) | pflags;
+			newflags = (dp->flags & mods->mask) | mods->flags;
 			if (newflags == dp->flags)
 				continue;
 #ifdef CONFIG_JUMP_LABEL
 			if (dp->flags & _DPRINTK_FLAGS_PRINT) {
-				if (!(pflags & _DPRINTK_FLAGS_PRINT))
+				if (!(mods->flags & _DPRINTK_FLAGS_PRINT))
 					static_branch_disable(&dp->key.dd_key_true);
-			} else if (pflags & _DPRINTK_FLAGS_PRINT)
+			} else if (mods->flags & _DPRINTK_FLAGS_PRINT)
 				static_branch_enable(&dp->key.dd_key_true);
 #endif
 			dp->flags = newflags;
@@ -413,14 +418,14 @@ static int ddebug_parse_query(char *words[], int nwords,
 	return 0;
 }
 
-static int ddebug_read_flags(const char *str, unsigned int *flags)
+static int ddebug_read_flags(const char *str, struct flagsettings *f)
 {
 	int i;
 
 	for (; *str ; ++str) {
 		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
 			if (*str == opt_array[i].opt_char) {
-				*flags |= opt_array[i].flag;
+				f->flags |= opt_array[i].flag;
 				break;
 			}
 		}
@@ -429,7 +434,7 @@ static int ddebug_read_flags(const char *str, unsigned int *flags)
 			return -EINVAL;
 		}
 	}
-	vpr_info("flags=0x%x\n", *flags);
+	vpr_info("flags=0x%x mask=0x%x\n", f->flags, f->mask);
 	return 0;
 }
 
@@ -439,10 +444,8 @@ static int ddebug_read_flags(const char *str, unsigned int *flags)
  * flags fields of matched _ddebug's.  Returns 0 on success
  * or <0 on error.
  */
-static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
-			       unsigned int *maskp)
+static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
 {
-	unsigned flags = 0;
 	int op;
 
 	switch (*str) {
@@ -457,31 +460,30 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 	}
 	vpr_info("op='%c'\n", op);
 
-	if (ddebug_read_flags(str, &flags))
+	if (ddebug_read_flags(str, mods))
 		return -EINVAL;
 
-	/* calculate final *flagsp, *maskp according to mask and op */
+	/* calculate final flags, mask based upon op */
 	switch (op) {
 	case '=':
-		*maskp = 0;
-		*flagsp = flags;
+		mods->mask = 0;
 		break;
 	case '+':
-		*maskp = ~0U;
-		*flagsp = flags;
+		mods->mask = ~0U;
 		break;
 	case '-':
-		*maskp = ~flags;
-		*flagsp = 0;
+		mods->mask = ~mods->flags;
+		mods->flags = 0;
 		break;
 	}
-	vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
+	vpr_info("*flagsp=0x%x *maskp=0x%x\n", mods->flags, mods->mask);
+
 	return 0;
 }
 
 static int ddebug_exec_query(char *query_string, const char *modname)
 {
-	unsigned int flags = 0, mask = 0;
+	struct flagsettings mods = {};
 	struct ddebug_query query;
 #define MAXWORDS 9
 	int nwords, nfound;
@@ -493,7 +495,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		return -EINVAL;
 	}
 	/* check flags 1st (last arg) so query is pairs of spec,val */
-	if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) {
+	if (ddebug_parse_flags(words[nwords-1], &mods)) {
 		pr_err("flags parse failed\n");
 		return -EINVAL;
 	}
@@ -502,7 +504,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		return -EINVAL;
 	}
 	/* actually go and implement the change */
-	nfound = ddebug_change(&query, flags, mask);
+	nfound = ddebug_change(&query, &mods);
 	vpr_info_dq(&query, nfound ? "applied" : "no-match");
 
 	return nfound;
-- 
2.26.2

[PATCH 12/16] dyndbg: add filter parameter to ddebug_parse_flags

[Jim Cromie]

Add a new *filter param to ddebug_parse_flags(), allowing it to
communicate optional filter flags back to its caller: ddebug_change()

Also, ddebug_change doesn't alter any of its arguments, including its 2
new ones; mods, filter.  Say so by adding const modifier to them.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 2ecabfd3f432..32eb7d9545c7 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -146,7 +146,8 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
  * logs the changes.  Takes ddebug_lock.
  */
 static int ddebug_change(const struct ddebug_query *query,
-			 struct flagsettings *mods)
+			 const struct flagsettings *mods,
+			 const struct flagsettings *filter)
 {
 	int i;
 	struct ddebug_table *dt;
@@ -444,7 +445,10 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
  * flags fields of matched _ddebug's.  Returns 0 on success
  * or <0 on error.
  */
-static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
+
+static int ddebug_parse_flags(const char *str,
+			      struct flagsettings *mods,
+			      struct flagsettings *filter)
 {
 	int op;
 
@@ -476,7 +480,9 @@ static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
 		mods->flags = 0;
 		break;
 	}
-	vpr_info("*flagsp=0x%x *maskp=0x%x\n", mods->flags, mods->mask);
+
+	vpr_info("mods:flags=0x%x,mask=0x%x filter:flags=0x%x,mask=0x%x\n",
+		 mods->flags, mods->mask, filter->flags, filter->mask);
 
 	return 0;
 }
@@ -484,6 +490,7 @@ static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
 static int ddebug_exec_query(char *query_string, const char *modname)
 {
 	struct flagsettings mods = {};
+	struct flagsettings filter = {};
 	struct ddebug_query query;
 #define MAXWORDS 9
 	int nwords, nfound;
@@ -495,7 +502,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		return -EINVAL;
 	}
 	/* check flags 1st (last arg) so query is pairs of spec,val */
-	if (ddebug_parse_flags(words[nwords-1], &mods)) {
+	if (ddebug_parse_flags(words[nwords-1], &mods, &filter)) {
 		pr_err("flags parse failed\n");
 		return -EINVAL;
 	}
@@ -504,7 +511,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		return -EINVAL;
 	}
 	/* actually go and implement the change */
-	nfound = ddebug_change(&query, &mods);
+	nfound = ddebug_change(&query, &mods, &filter);
 	vpr_info_dq(&query, nfound ? "applied" : "no-match");
 
 	return nfound;
-- 
2.26.2

Re: [PATCH 12/16] dyndbg: add filter parameter to ddebug_parse_flags

[Jason Baron]

On 6/5/20 12:26 PM, Jim Cromie wrote:
> Add a new *filter param to ddebug_parse_flags(), allowing it to
> communicate optional filter flags back to its caller: ddebug_change()
>

I think you meant ddebug_exec_query() here?

Thanks,


-Jason


> Also, ddebug_change doesn't alter any of its arguments, including its 2
> new ones; mods, filter.  Say so by adding const modifier to them.
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  lib/dynamic_debug.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 2ecabfd3f432..32eb7d9545c7 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -146,7 +146,8 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>   * logs the changes.  Takes ddebug_lock.
>   */
>  static int ddebug_change(const struct ddebug_query *query,
> -			 struct flagsettings *mods)
> +			 const struct flagsettings *mods,
> +			 const struct flagsettings *filter)
>  {
>  	int i;
>  	struct ddebug_table *dt;
> @@ -444,7 +445,10 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
>   * flags fields of matched _ddebug's.  Returns 0 on success
>   * or <0 on error.
>   */
> -static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
> +
> +static int ddebug_parse_flags(const char *str,
> +			      struct flagsettings *mods,
> +			      struct flagsettings *filter)
>  {
>  	int op;
>  
> @@ -476,7 +480,9 @@ static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
>  		mods->flags = 0;
>  		break;
>  	}
> -	vpr_info("*flagsp=0x%x *maskp=0x%x\n", mods->flags, mods->mask);
> +
> +	vpr_info("mods:flags=0x%x,mask=0x%x filter:flags=0x%x,mask=0x%x\n",
> +		 mods->flags, mods->mask, filter->flags, filter->mask);
>  
>  	return 0;
>  }
> @@ -484,6 +490,7 @@ static int ddebug_parse_flags(const char *str, struct flagsettings *mods)
>  static int ddebug_exec_query(char *query_string, const char *modname)
>  {
>  	struct flagsettings mods = {};
> +	struct flagsettings filter = {};
>  	struct ddebug_query query;
>  #define MAXWORDS 9
>  	int nwords, nfound;
> @@ -495,7 +502,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
>  		return -EINVAL;
>  	}
>  	/* check flags 1st (last arg) so query is pairs of spec,val */
> -	if (ddebug_parse_flags(words[nwords-1], &mods)) {
> +	if (ddebug_parse_flags(words[nwords-1], &mods, &filter)) {
>  		pr_err("flags parse failed\n");
>  		return -EINVAL;
>  	}
> @@ -504,7 +511,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
>  		return -EINVAL;
>  	}
>  	/* actually go and implement the change */
> -	nfound = ddebug_change(&query, &mods);
> +	nfound = ddebug_change(&query, &mods, &filter);
>  	vpr_info_dq(&query, nfound ? "applied" : "no-match");
>  
>  	return nfound;
> 

[PATCH 13/16] dyndbg: extend ddebug_parse_flags to accept optional leading filter-flags

[Jim Cromie]

change ddebug_parse_flags to accept optional filterflags before OP.
this now sets the parameter added in ~1

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 .../admin-guide/dynamic-debug-howto.rst       | 18 +++++++----
 lib/dynamic_debug.c                           | 30 ++++++++++---------
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 880d33d1782f..250ab30e2080 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -212,13 +212,19 @@ line
 	line -1605          // the 1605 lines from line 1 to line 1605
 	line 1600-          // all lines from line 1600 to the end of the file
 
-The flags specification comprises a change operation followed
-by one or more flag characters.  The change operation is one
-of the characters::
+Flags Specification::
 
-  -    remove the given flags
-  +    add the given flags
-  =    set the flags to the given flags
+  flagspec	::= filterflags? OP modflags
+  filterflags	::= flagset
+  modflags	::= flagset
+  flagset	::= ([pfmltu_] | [PFMLTU_])+	# also cant have pP etc
+  OP		::= [-+=]
+
+OP: modify callsites per following flagset::
+
+  -    remove the following flags
+  +    add the following flags
+  =    set the flags to the following flags
 
 The flags are::
 
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 32eb7d9545c7..90061833ef3f 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -440,34 +440,36 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
 }
 
 /*
- * Parse `str' as a flags specification, format [-+=][p]+.
- * Sets up *maskp and *flagsp to be used when changing the
- * flags fields of matched _ddebug's.  Returns 0 on success
- * or <0 on error.
+ * Parse `str' as a flags-spec, ie: [pfmlt_]*[-+=][pfmlt_]+
+ * Fills flagsettings provided.  Returns 0 on success or <0 on error.
  */
-
 static int ddebug_parse_flags(const char *str,
 			      struct flagsettings *mods,
 			      struct flagsettings *filter)
 {
 	int op;
+	char *opp = strpbrk(str, "-+=");
 
-	switch (*str) {
-	case '+':
-	case '-':
-	case '=':
-		op = *str++;
-		break;
-	default:
-		pr_err("bad flag-op %c, at start of %s\n", *str, str);
+	if (!opp) {
+		pr_err("no OP given in %s\n", str);
 		return -EINVAL;
 	}
+	op = *opp;
 	vpr_info("op='%c'\n", op);
 
+	if (opp != str) {
+		/* filterflags precedes OP, grab it */
+		*opp++ = '\0';
+		if (ddebug_read_flags(str, filter))
+			return -EINVAL;
+		str = opp;
+	} else
+		str++;
+
 	if (ddebug_read_flags(str, mods))
 		return -EINVAL;
 
-	/* calculate final flags, mask based upon op */
+	/* calculate final mods: flags, mask based upon op */
 	switch (op) {
 	case '=':
 		mods->mask = 0;
-- 
2.26.2

[PATCH 14/16] dyndbg: prefer declarative init in caller, to memset in callee

[Jim Cromie]

drop memset in ddebug_parse_query, instead initialize the stack
variable in the caller; let the compiler decide how to do it.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 90061833ef3f..f0c0c31e91ea 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -372,7 +372,6 @@ static int ddebug_parse_query(char *words[], int nwords,
 		pr_err("expecting pairs of match-spec <value>\n");
 		return -EINVAL;
 	}
-	memset(query, 0, sizeof(*query));
 
 	if (modname)
 		/* support $modname.dyndbg=<multiple queries> */
@@ -493,7 +492,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 {
 	struct flagsettings mods = {};
 	struct flagsettings filter = {};
-	struct ddebug_query query;
+	struct ddebug_query query = {};
 #define MAXWORDS 9
 	int nwords, nfound;
 	char *words[MAXWORDS];
-- 
2.26.2

[PATCH 15/16] dyndbg: add user-flag, negating-flags, and filtering on flags

[Jim Cromie]

1. Add a user-flag [u] which works like the [pfmlt] flags, but has no
effect on callsite behavior; it allows incremental marking of
arbitrary sets of callsites.

2. Add [PFMLTU] flags, which negate their counterparts; P===!p etc.
And in ddebug_read_flags():
   current code does:	[pfmltu_] -> flags
   copy it to:		[PFMLTU_] -> mask

also disallow both of a pair: ie no 'pP', no true & false.

3. Add filtering ops into ddebug_change(), right after all the
callsite-property selections are complete.  These filter on the
callsite's current flagstate before applying modflags.

Why ?

The new user flag facilitates batching of changes.  By marking
individual callsites with 'u', a user can compose an arbitrary set of
changes, then activate them together by filtering on 'u':

  #> echo 'file foo.c +u; file bar.c +u' > control
  #> echo 'u+p' > control

The user flag isn't strictly needed, but with it you can avoid using
[fmlt] flags for marking, which would alter logging when enabled.

The negating flags allow filtering on either 0/1 for each flag.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 .../admin-guide/dynamic-debug-howto.rst       | 31 ++++++++++++++++---
 include/linux/dynamic_debug.h                 |  1 +
 lib/dynamic_debug.c                           | 31 ++++++++++++++-----
 3 files changed, 51 insertions(+), 12 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 250ab30e2080..26a19f511afa 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -233,16 +233,39 @@ The flags are::
   l    Include line number in the printed message
   m    Include module name in the printed message
   t    Include thread ID in messages not generated from interrupt context
+  u    user flag, to mark callsites into a group
   _    No flags are set. (Or'd with others on input)
 
-For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only ``p`` flag
-have meaning, other flags ignored.
+Additionally, the flag-chars ``[pflmtu]`` have negating flag-chars
+``[PFMLTU]``, which invert the meanings above.  Their use follows.
+
+Using Filters::
+
+Filter-flags specify an optional additional selector on pr_debug
+callsites; with them you can compose an arbitrary set of callsites, by
+iteratively marking them with ``+u``, then enabling them all with
+``u+p``.  You can also use ``fmlt`` flags for this, unless the format
+changes are inconvenient.
+
+Filters can also contain the negating flags, like ``UF``, which select
+only callsites with ``u`` and ``f`` cleared.
+
+Flagsets cannot contain ``pP`` etc, a flag cannot be true and false.
+
+modflags containing upper-case flags is reserved/undefined for now.
+inverted-flags are currently ignored, usage gets trickier if given
+``-pXy``, it should leave x set.
+
+Notes::
+
+For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
+``p`` flag has meaning, other flags are ignored.
 
 For display, the flags are preceded by ``=``
 (mnemonic: what the flags are currently equal to).
 
-Note the regexp ``^[-+=][flmpt_]+$`` matches a flags specification.
-To clear all flags at once, use ``=_`` or ``-flmpt``.
+Note the regexp ``^[-+=][flmptu_]+$`` matches a flags specification.
+To clear all flags at once, use ``=_`` or ``-flmptu``.
 
 
 Debug messages during Boot Process
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 802480ea8708..a5d76f8f6b40 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -32,6 +32,7 @@ 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_USR		(1<<5)
 #if defined DEBUG
 #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
 #else
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index f0c0c31e91ea..ee92e93cf23d 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -83,13 +83,14 @@ static inline const char *trim_prefix(const char *path)
 	return path + skip;
 }
 
-static struct { unsigned flag:8; char opt_char; } opt_array[] = {
-	{ _DPRINTK_FLAGS_PRINT, 'p' },
-	{ _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
-	{ _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
-	{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
-	{ _DPRINTK_FLAGS_INCL_TID, 't' },
-	{ _DPRINTK_FLAGS_NONE, '_' },
+static struct { unsigned flag:8; char opt_char, not_char; } opt_array[] = {
+	{ _DPRINTK_FLAGS_PRINT,		'p', 'P' },
+	{ _DPRINTK_FLAGS_INCL_MODNAME,	'm', 'M' },
+	{ _DPRINTK_FLAGS_INCL_FUNCNAME,	'f', 'F' },
+	{ _DPRINTK_FLAGS_INCL_LINENO,	'l', 'L' },
+	{ _DPRINTK_FLAGS_INCL_TID,	't', 'T' },
+	{ _DPRINTK_FLAGS_NONE,		'_', '_' },
+	{ _DPRINTK_FLAGS_USR,		'u', 'U' },
 };
 
 struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
@@ -194,6 +195,13 @@ static int ddebug_change(const struct ddebug_query *query,
 			    dp->lineno > query->last_lineno)
 				continue;
 
+			/* filter for required flags */
+			if ((dp->flags & filter->flags) != filter->flags)
+				continue;
+			/* filter on prohibited bits */
+			if ((~dp->flags & filter->mask) != filter->mask)
+				continue;
+
 			nfound++;
 
 			newflags = (dp->flags & mods->mask) | mods->flags;
@@ -427,10 +435,17 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
 			if (*str == opt_array[i].opt_char) {
 				f->flags |= opt_array[i].flag;
 				break;
+			} else if (*str == opt_array[i].not_char) {
+				f->mask |= opt_array[i].flag;
+				break;
 			}
 		}
 		if (i < 0) {
-			pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
+			pr_err("unknown flag '%c'", *str);
+			return -EINVAL;
+		}
+		if (f->flags & f->mask) {
+			pr_err("flag '%c' conflicts with previous\n", *str);
 			return -EINVAL;
 		}
 	}
-- 
2.26.2

[PATCH 16/16] dyndbg: allow negating flag-chars in modflags

[Jim Cromie]

Extend flags modifications to allow [PFMLTU] negating flags.
This allows control-queries like:

  #> Q () { echo file inode.c $* > control } # to type less
  #> Q -P	# same as +p
  #> Q +U	# same as -u
  #> Q u-P	# same as u+p

This allows flags in a callsite to be simultaneously set and cleared,
while still starting with the current flagstate (with +- ops).
Generally, you chose -p or +p 1st, then set or clear flags
accordingly.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 Documentation/admin-guide/dynamic-debug-howto.rst | 10 ++++++----
 lib/dynamic_debug.c                               |  6 ++++--
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 26a19f511afa..45470c9f0dad 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -252,9 +252,11 @@ only callsites with ``u`` and ``f`` cleared.
 
 Flagsets cannot contain ``pP`` etc, a flag cannot be true and false.
 
-modflags containing upper-case flags is reserved/undefined for now.
-inverted-flags are currently ignored, usage gets trickier if given
-``-pXy``, it should leave x set.
+modflags may contain upper-case flags also, using these lets you
+invert the flag setting implied by the OP; '-pU' means disable
+printing, and mark that callsite with the user-flag to create a group,
+for optional further manipulation.  Generally, '+p' and '-p' is your
+main choice, and use of negating flags in modflags is rare.
 
 Notes::
 
@@ -264,7 +266,7 @@ For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
 For display, the flags are preceded by ``=``
 (mnemonic: what the flags are currently equal to).
 
-Note the regexp ``^[-+=][flmptu_]+$`` matches a flags specification.
+Note the regexp ``/^[-+=][flmptu_]+$/i`` matches a flags specification.
 To clear all flags at once, use ``=_`` or ``-flmptu``.
 
 
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index ee92e93cf23d..63ae6f77a0e4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -485,15 +485,17 @@ static int ddebug_parse_flags(const char *str,
 
 	/* calculate final mods: flags, mask based upon op */
 	switch (op) {
+		unsigned int tmp;
 	case '=':
 		mods->mask = 0;
 		break;
 	case '+':
-		mods->mask = ~0U;
+		mods->mask = ~mods->mask;
 		break;
 	case '-':
+		tmp = mods->mask;
 		mods->mask = ~mods->flags;
-		mods->flags = 0;
+		mods->flags = tmp;
 		break;
 	}
 
-- 
2.26.2

Re: [PATCH 00/16] dynamic_debug: cleanups, 2 features

[Jason Baron]

On 6/5/20 12:26 PM, Jim Cromie wrote:
> Patchset starts with 7 "cleanups";
> - it changes section name from vague "__verbose" to "__dyndbg"
> - cleaner docs, drop obsolete comment & useless debug prints, refine
>   verbosity, fix a BUG_ON, ram reporting miscounts.
> 
> It adds a few query parsing conveniences;
> accept combined file:line & file:func forms
> 
>   file inode.c:100-200		# file & line-range
>   file inode.c:start_*		# file & function
>

So I like the shortened notation there.

> Then it expands flags:
> 
> Adds 'u' user flag, allowing user to compose an arbitrary set of
> callsites by marking them with 'u', without altering current
> print-modifying flags.
> 
> Adds 'PFMLTU' flags, which negate their lower-case counterparts.
> 
> Extends flags-spec with filter-flags, which select callsites for
> modification based upon their current flags.  This lets user activate
> the set of callsites marked with 'u' in a batch.
> 
>   echo 'u+p' > control
> 

I'm wondering if users are really going to use these and how much they
simplify things? Do you find them useful while debugging issues?

Especially now that now that we are looking to let people define
groupings.

Thanks,

-Jason

Re: [PATCH 00/16] dynamic_debug: cleanups, 2 features

[jim.cromie]

On Fri, Jun 12, 2020 at 3:31 PM Jason Baron <jbaron@akamai.com> wrote:
>
>
>
> On 6/5/20 12:26 PM, Jim Cromie wrote:
> > Patchset starts with 7 "cleanups";
> > - it changes section name from vague "__verbose" to "__dyndbg"
> > - cleaner docs, drop obsolete comment & useless debug prints, refine
> >   verbosity, fix a BUG_ON, ram reporting miscounts.
> >
> > It adds a few query parsing conveniences;
> > accept combined file:line & file:func forms
> >
> >   file inode.c:100-200                # file & line-range
> >   file inode.c:start_*                # file & function
> >
>
> So I like the shortened notation there.
>
> > Then it expands flags:
> >
> > Adds 'u' user flag, allowing user to compose an arbitrary set of
> > callsites by marking them with 'u', without altering current
> > print-modifying flags.
> >
> > Adds 'PFMLTU' flags, which negate their lower-case counterparts.
> >
> > Extends flags-spec with filter-flags, which select callsites for
> > modification based upon their current flags.  This lets user activate
> > the set of callsites marked with 'u' in a batch.
> >
> >   echo 'u+p' > control
> >
>
> I'm wondering if users are really going to use these and how much they
> simplify things? Do you find them useful while debugging issues?
>
> Especially now that now that we are looking to let people define
> groupings.
>
> Thanks,
>
> -Jason

so we have
1- u flag - in modflags, allows marking of sets
2- filterflags - constrain matching sites to those marked
    plus any other subcondition you might want on your marked set

3- negating flags

in filters, they allow complete match to all the bits.
dont want to touch callsites marked with Pt ?
(marked with t, without printing)  now you can.

filters let you use current flagstate to select subsets of " +p >control"
+negations gives complete selectivity on that flagstate

in modflags theyre more convenience,
but setting and clearing 2+ bits atomically
lets you both use the u bit to enable printing
(inc module name filename) and retire that use of u,
or to change the logging output subtly (by dropping threads display,
or module-name)

I cant say its essential, but its so cheap (last patch) once negating
flags are in place,
which are needed for full selectivity filtering.

thanks
Jim

[PATCH 05/16] dyndbg: fix overcounting of ram used by dyndbg

[Jim Cromie]

during dyndbg init, verbose logging prints its ram overhead.  It
counted strlens of struct _ddebug's 4 string members, in all callsite
entries, which would be approximately correct if each had been
mallocd.  But they are pointers into shared .rodata; for example, all
10 kobject callsites have identical filename, module values.

Its best not to count that memory at all, since we cannot know they
were linked in because of CONFIG_DYNAMIC_DEBUG=y, and we want to
report a number that reflects what ram is saved by deconfiguring it.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 0a4588fe342e..b5fb0aa0fbc3 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1008,7 +1008,6 @@ static int __init dynamic_debug_init(void)
 	char *cmdline;
 	int ret = 0;
 	int n = 0, entries = 0, modct = 0;
-	int verbose_bytes = 0;
 
 	if (__start___dyndbg == __stop___dyndbg) {
 		pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
@@ -1019,9 +1018,6 @@ static int __init dynamic_debug_init(void)
 	iter_start = iter;
 	for (; iter < __stop___dyndbg; iter++) {
 		entries++;
-		verbose_bytes += strlen(iter->modname) + strlen(iter->function)
-			+ strlen(iter->filename) + strlen(iter->format);
-
 		if (strcmp(modname, iter->modname)) {
 			modct++;
 			ret = ddebug_add_module(iter_start, n, modname);
@@ -1038,9 +1034,9 @@ static int __init dynamic_debug_init(void)
 		goto out_err;
 
 	ddebug_init_success = 1;
-	vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
+	vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in __dyndbg section\n",
 		 modct, entries, (int)(modct * sizeof(struct ddebug_table)),
-		 verbose_bytes + (int)(__stop___dyndbg - __start___dyndbg));
+		 (int)(entries * sizeof(struct _ddebug)));
 
 	/* apply ddebug_query boot param, dont unload tables on err */
 	if (ddebug_setup_string[0] != '\0') {
-- 
2.23.0

Re: [PATCH 05/16] dyndbg: fix overcounting of ram used by dyndbg

[Rasmus Villemoes]

On 27/11/2019 18.50, Jim Cromie wrote:
> during dyndbg init, verbose logging prints its ram overhead.  It
> counted strlens of struct _ddebug's 4 string members, in all callsite
> entries, which would be approximately correct if each had been
> mallocd.  But they are pointers into shared .rodata; for example, all
> 10 kobject callsites have identical filename, module values.
> 
> Its best not to count that memory at all, since we cannot know they
> were linked in because of CONFIG_DYNAMIC_DEBUG=y, and we want to
> report a number that reflects what ram is saved by deconfiguring it.

That, and we avoid 1000s of (mostly cache-cold) strlen() calls during boot.

Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

I'll see if I can find time to review the other patches, then I think
you need to resend with Andrew on the cc-list (added here). I think he's
the one routing lib/dynamic_debug.c patches.

Rasmus