[PATCH v8 20/43] dyndbg: tighten fn-sig of ddebug_apply_class_bitmap

[Jim Cromie via B4 Relay <devnull+jim.cromie.gmail.com@kernel.org>]

From: Jim Cromie <jim.cromie@gmail.com>

old_bits arg is currently a pointer to the input bits, but this could
allow inadvertent changes to the input by the fn.  Disallow this.
And constify new_bits while here.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v2: move RvB after SoB
---
 lib/dynamic_debug.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 82c4d60d931e..e0e3cadd82bd 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -620,7 +620,8 @@ static int ddebug_exec_queries(char *query, const char *modname)
 
 /* apply a new class-param setting */
 static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
-				     unsigned long *new_bits, unsigned long *old_bits,
+				     const unsigned long *new_bits,
+				     const unsigned long old_bits,
 				     const char *query_modname)
 {
 #define QUERY_SIZE 128
@@ -629,12 +630,12 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
 	int matches = 0;
 	int bi, ct;
 
-	if (*new_bits != *old_bits)
+	if (*new_bits != old_bits)
 		v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
-			  *old_bits, query_modname ?: "'*'");
+			  old_bits, query_modname ?: "'*'");
 
 	for (bi = 0; bi < map->length; bi++) {
-		if (test_bit(bi, new_bits) == test_bit(bi, old_bits))
+		if (test_bit(bi, new_bits) == test_bit(bi, &old_bits))
 			continue;
 
 		snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi],
@@ -646,9 +647,9 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
 		v2pr_info("bit_%d: %d matches on class: %s -> 0x%lx\n", bi,
 			  ct, map->class_names[bi], *new_bits);
 	}
-	if (*new_bits != *old_bits)
+	if (*new_bits != old_bits)
 		v2pr_info("applied bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
-			  *old_bits, query_modname ?: "'*'");
+			  old_bits, query_modname ?: "'*'");
 
 	return matches;
 }
@@ -690,7 +691,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
 		}
 		old_val = READ_ONCE(*dcp->bits);
 		v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
-		totct += ddebug_apply_class_bitmap(dcp, &inrep, &old_val, mod_name);
+		totct += ddebug_apply_class_bitmap(dcp, &inrep, old_val, mod_name);
 		WRITE_ONCE(*dcp->bits, inrep);
 		break;
 	case DD_CLASS_TYPE_LEVEL_NUM:
@@ -704,7 +705,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
 		old_bits = CLASSMAP_BITMASK(old_val);
 		new_bits = CLASSMAP_BITMASK(inrep);
 		v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp));
-		totct += ddebug_apply_class_bitmap(dcp, &new_bits, &old_bits, mod_name);
+		totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, mod_name);
 		WRITE_ONCE(*dcp->lvl, inrep);
 		break;
 	default:

-- 
2.55.0