linux-kernel - [PATCH v3 18/21] dyndbg: add filter channel to the internals

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Message-Id: <20200617162536.611386-21-jim.cromie@gmail.com>
Date:   Wed, 17 Jun 2020 10:25:33 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, linux-kernel@...r.kernel.org,
        akpm@...uxfoundation.org, gregkh@...uxfoundation.org
Cc:     linux@...musvillemoes.dk, Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v3 18/21] dyndbg: add filter channel to the internals

Once again, adjust the interface between 3 static functions:

 - ddebug_exec_query calls ..
   - ddebug_parse_query - unchanged here, mentioned for context
   - ddebug_parse_flags, to read the modifying flags
   - ddebug_change, to apply mods to callsites that match the query

This time, add a 2nd flag_settings variable int ddebug_exec_query(),
to specify a secondary constraint on callsites which match the query,
and which are therefore about to be modified.

Here, we only add the channel; ddebug_parse_flags doesnt fill the
filter, and ddebug_change doesnt act upon it.

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@...il.com>
---
 lib/dynamic_debug.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8400e4f90b67..0fcc688789f4 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 flag_settings *modifiers)
+			 const struct flag_settings *modifiers,
+			 const struct flag_settings *filter)
 {
 	int i;
 	struct ddebug_table *dt;
@@ -456,7 +457,9 @@ static int ddebug_read_flags(const char *str, struct flag_settings *modifiers)
  * flags fields of matched _ddebug's.  Returns 0 on success
  * or <0 on error.
  */
-static int ddebug_parse_flags(const char *str, struct flag_settings *modifiers)
+static int ddebug_parse_flags(const char *str,
+			      struct flag_settings *modifiers,
+			      struct flag_settings *filter)
 {
 	int op;
 
@@ -489,7 +492,8 @@ static int ddebug_parse_flags(const char *str, struct flag_settings *modifiers)
 		modifiers->flags = 0;
 		break;
 	}
-	vpr_info("*flagsp=0x%x *maskp=0x%x\n", modifiers->flags, modifiers->mask);
+	vpr_info("mods:flags=0x%x,mask=0x%x filter:flags=0x%x,mask=0x%x\n",
+		 modifiers->flags, modifiers->mask, filter->flags, filter->mask);
 
 	return 0;
 }
@@ -498,6 +502,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 {
 	struct flag_settings modifiers = {};
 	struct ddebug_query query = {};
+	struct flag_settings filter = {};
 #define MAXWORDS 9
 	int nwords, nfound;
 	char *words[MAXWORDS];
@@ -508,7 +513,7 @@ 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], &modifiers)) {
+	if (ddebug_parse_flags(words[nwords-1], &modifiers, &filter)) {
 		pr_err("flags parse failed\n");
 		return -EINVAL;
 	}
@@ -517,7 +522,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		return -EINVAL;
 	}
 	/* actually go and implement the change */
-	nfound = ddebug_change(&query, &modifiers);
+	nfound = ddebug_change(&query, &modifiers, &filter);
 	vpr_info_dq(&query, nfound ? "applied" : "no-match");
 
 	return nfound;
-- 
2.26.2