perf maps: Fixup maps_by_name when modifying maps_by_address

We can't just replacing the map in the maps_by_address and not touching
on the maps_by_name, that would leave the refcount as 1 and thus trip
another consistency check, this one:

  perf: util/maps.c:110: check_invariants:
  	Assertion `refcount_read(map__refcnt(map)) > 1' failed.

  106         /*
  107          * Maps by name maps should be in maps_by_address, so
  108          * the reference count should be higher.
  109          */
  110         assert(refcount_read(map__refcnt(map)) > 1);

Committer notice:

Initialize the newly added 'ni' variable, that really can't be
accessed unitialized trips some gcc versions, like:

  12    20.00 archlinux:base                : FAIL gcc version 13.2.1 20230801 (GCC)
    util/maps.c: In function ‘__maps__fixup_overlap_and_insert’:
    util/maps.c:896:54: error: ‘ni’ may be used uninitialized [-Werror=maybe-uninitialized]
      896 |                                 map__put(maps_by_name[ni]);
          |                                                      ^
    util/maps.c:816:25: note: ‘ni’ was declared here
      816 |         unsigned int i, ni;
          |                         ^~
    cc1: all warnings being treated as errors
    make[3]: *** [/git/perf-6.14.0-rc1/tools/build/Makefile.build:138: util] Error 2

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/lkml/Z79std66tPq-nqsD@google.com
Link: https://lore.kernel.org/r/20250228211734.33781-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 8c5f5d79cd24a6bce0ddb8a923c62e68d77feb09..77df9701d5ad7de3c01fb06135bdb1db04aeb9c6 100644 (file)
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -813,7 +813,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
 {
        int err = 0;
        FILE *fp = debug_file();
-       unsigned int i;
+       unsigned int i, ni = INT_MAX; // Some gcc complain, but depends on maps_by_name...
 
        if (!maps__maps_by_address_sorted(maps))
                __maps__sort_by_address(maps);
@@ -824,6 +824,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
         */
        for (i = first_ending_after(maps, new); i < maps__nr_maps(maps); ) {
                struct map **maps_by_address = maps__maps_by_address(maps);
+               struct map **maps_by_name = maps__maps_by_name(maps);
                struct map *pos = maps_by_address[i];
                struct map *before = NULL, *after = NULL;
 
@@ -843,6 +844,9 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
                        map__fprintf(pos, fp);
                }
 
+               if (maps_by_name)
+                       ni = maps__by_name_index(maps, pos);
+
                /*
                 * Now check if we need to create new maps for areas not
                 * overlapped by the new map:
@@ -887,6 +891,12 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
                if (before) {
                        map__put(maps_by_address[i]);
                        maps_by_address[i] = before;
+
+                       if (maps_by_name) {
+                               map__put(maps_by_name[ni]);
+                               maps_by_name[ni] = map__get(before);
+                       }
+
                        /* Maps are still ordered, go to next one. */
                        i++;
                        if (after) {
@@ -908,6 +918,12 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
                         */
                        map__put(maps_by_address[i]);
                        maps_by_address[i] = map__get(new);
+
+                       if (maps_by_name) {
+                               map__put(maps_by_name[ni]);
+                               maps_by_name[ni] = map__get(new);
+                       }
+
                        err = __maps__insert_sorted(maps, i + 1, after, NULL);
                        map__put(after);
                        check_invariants(maps);
@@ -926,6 +942,12 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new)
                                 */
                                map__put(maps_by_address[i]);
                                maps_by_address[i] = map__get(new);
+
+                               if (maps_by_name) {
+                                       map__put(maps_by_name[ni]);
+                                       maps_by_name[ni] = map__get(new);
+                               }
+
                                check_invariants(maps);
                                return err;
                        }