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.cro...@gmail.com>
---
 lib/dynamic_debug.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8158943b350d..8beb98a831f5 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -593,7 +593,8 @@ 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
@@ -602,12 +603,12 @@ 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],
@@ -619,9 +620,9 @@ 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;
 }
@@ -678,7 +679,7 @@ static int param_set_dyndbg_classnames(const char *instr, 
const struct kernel_pa
                                continue;
                        }
                        curr_bits ^= BIT(cls_id);
-                       totct += ddebug_apply_class_bitmap(dcp, &curr_bits, 
dcp->bits, NULL);
+                       totct += ddebug_apply_class_bitmap(dcp, &curr_bits, 
*dcp->bits, NULL);
                        *dcp->bits = curr_bits;
                        v2pr_info("%s: changed bit %d:%s\n", KP_NAME(kp), 
cls_id,
                                  map->class_names[cls_id]);
@@ -688,7 +689,7 @@ static int param_set_dyndbg_classnames(const char *instr, 
const struct kernel_pa
                        old_bits = CLASSMAP_BITMASK(*dcp->lvl);
                        curr_bits = CLASSMAP_BITMASK(cls_id + (wanted ? 1 : 0 
));
 
-                       totct += ddebug_apply_class_bitmap(dcp, &curr_bits, 
&old_bits, NULL);
+                       totct += ddebug_apply_class_bitmap(dcp, &curr_bits, 
old_bits, NULL);
                        *dcp->lvl = (cls_id + (wanted ? 1 : 0));
                        v2pr_info("%s: changed bit-%d: \"%s\" %lx->%lx\n", 
KP_NAME(kp), cls_id,
                                  map->class_names[cls_id], old_bits, 
curr_bits);
@@ -742,7 +743,7 @@ static int param_set_dyndbg_module_classes(const char 
*instr,
                        inrep &= CLASSMAP_BITMASK(map->length);
                }
                v2pr_info("bits:0x%lx > %s.%s\n", inrep, modnm ?: "*", 
KP_NAME(kp));
-               totct += ddebug_apply_class_bitmap(dcp, &inrep, dcp->bits, 
modnm);
+               totct += ddebug_apply_class_bitmap(dcp, &inrep, *dcp->bits, 
modnm);
                *dcp->bits = inrep;
                break;
        case DD_CLASS_TYPE_LEVEL_NUM:
@@ -755,7 +756,7 @@ static int param_set_dyndbg_module_classes(const char 
*instr,
                old_bits = CLASSMAP_BITMASK(*dcp->lvl);
                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, 
modnm);
+               totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, 
modnm);
                *dcp->lvl = inrep;
                break;
        default:
-- 
2.41.0

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