[PATCH v5 15/18] dyndbg: combine flags & mask into a struct, simplify with it

From: Jim Cromie <jim.cromie@gmail.com>
To: jbaron@akamai.com, linux-kernel@vger.kernel.org,
	akpm@linuxfoundation.org, gregkh@linuxfoundation.org
Cc: linux@rasmusvillemoes.dk, Jim Cromie <jim.cromie@gmail.com>
Subject: [PATCH v5 15/18] dyndbg: combine flags & mask into a struct, simplify with it
Date: Sun, 19 Jul 2020 17:10:55 -0600	[thread overview]
Message-ID: <20200719231058.1586423-16-jim.cromie@gmail.com> (raw)
In-Reply-To: <20200719231058.1586423-1-jim.cromie@gmail.com>

flags & mask are used together everywhere, and are passed around
together between multiple functions; they belong together in a struct,
call that struct flag_settings.

Use struct flag_settings to rework 3 functions:
 - ddebug_exec_query - declares query and flag-settings,
   		     calls other 2, passing flags
 - ddebug_parse_flags - fills flag_settings and returns
 - ddebug_change - test all callsites against query,
   		   modify passing sites.

benefits:
 - bit-banging always needs flags & mask, best together.
 - simpler function signatures
 - 1 less parameter, less stack overhead

no functional changes

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 45 ++++++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index fad6c34c930d..c983049e986d 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -62,6 +62,11 @@ struct ddebug_iter {
 	unsigned int idx;
 };
 
+struct flag_settings {
+	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 flags, unsigned int mask)
+			 struct flag_settings *modifiers)
 {
 	int i;
 	struct ddebug_table *dt;
@@ -190,14 +195,14 @@ static int ddebug_change(const struct ddebug_query *query,
 
 			nfound++;
 
-			newflags = (dp->flags & mask) | flags;
+			newflags = (dp->flags & modifiers->mask) | modifiers->flags;
 			if (newflags == dp->flags)
 				continue;
 #ifdef CONFIG_JUMP_LABEL
 			if (dp->flags & _DPRINTK_FLAGS_PRINT) {
-				if (!(flags & _DPRINTK_FLAGS_PRINT))
+				if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT))
 					static_branch_disable(&dp->key.dd_key_true);
-			} else if (flags & _DPRINTK_FLAGS_PRINT)
+			} else if (modifiers->flags & _DPRINTK_FLAGS_PRINT)
 				static_branch_enable(&dp->key.dd_key_true);
 #endif
 			dp->flags = newflags;
@@ -431,11 +436,9 @@ static int ddebug_parse_query(char *words[], int nwords,
  * 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 flag_settings *modifiers)
 {
-	unsigned flags = 0;
-	int op = '=', i;
+	int op, i;
 
 	switch (*str) {
 	case '+':
@@ -452,7 +455,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 	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;
+				modifiers->flags |= opt_array[i].flag;
 				break;
 			}
 		}
@@ -461,30 +464,30 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 			return -EINVAL;
 		}
 	}
-	vpr_info("flags=0x%x\n", flags);
+	vpr_info("flags=0x%x\n", modifiers->flags);
 
-	/* calculate final *flagsp, *maskp according to mask and op */
+	/* calculate final flags, mask based upon op */
 	switch (op) {
 	case '=':
-		*maskp = 0;
-		*flagsp = flags;
+		/* modifiers->flags already set */
+		modifiers->mask = 0;
 		break;
 	case '+':
-		*maskp = ~0U;
-		*flagsp = flags;
+		modifiers->mask = ~0U;
 		break;
 	case '-':
-		*maskp = ~flags;
-		*flagsp = 0;
+		modifiers->mask = ~modifiers->flags;
+		modifiers->flags = 0;
 		break;
 	}
-	vpr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
+	vpr_info("*flagsp=0x%x *maskp=0x%x\n", modifiers->flags, modifiers->mask);
+
 	return 0;
 }
 
 static int ddebug_exec_query(char *query_string, const char *modname)
 {
-	unsigned int flags = 0, mask = 0;
+	struct flag_settings modifiers = {};
 	struct ddebug_query query = {};
 #define MAXWORDS 9
 	int nwords, nfound;
@@ -496,7 +499,7 @@ 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], &modifiers)) {
 		pr_err("flags parse failed\n");
 		return -EINVAL;
 	}
@@ -505,7 +508,7 @@ 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, &modifiers);
 	vpr_info_dq(&query, nfound ? "applied" : "no-match");
 
 	return nfound;
-- 
2.26.2

