perf maps: Locking tidy up of nr_maps

After this change maps__nr_maps is only used by tests, existing users
are migrated to maps__empty. Compute maps__empty under the read lock.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: James Clark <james.clark@arm.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Artem Savkov <asavkov@redhat.com>
Cc: bpf@vger.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240210031746.4057262-7-irogers@google.com

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 4911734..3da92f1 100644 (file)
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -440,7 +440,7 @@ static struct thread *findnew_guest_code(struct machine *machine,
                return NULL;
 
        /* Assume maps are set up if there are any */
-       if (maps__nr_maps(thread__maps(thread)))
+       if (!maps__empty(thread__maps(thread)))
                return thread;
 
        host_thread = machine__find_thread(host_machine, -1, pid);

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index 439cefa..53aea6d 100644 (file)
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -541,7 +541,13 @@ void maps__remove(struct maps *maps, struct map *map)
 
 bool maps__empty(struct maps *maps)
 {
-       return maps__nr_maps(maps) == 0;
+       bool res;
+
+       down_read(maps__lock(maps));
+       res = maps__nr_maps(maps) == 0;
+       up_read(maps__lock(maps));
+
+       return res;
 }
 
 bool maps__equal(struct maps *a, struct maps *b)
@@ -871,7 +877,7 @@ int maps__copy_from(struct maps *dest, struct maps *parent)
 
        parent_maps_by_address = maps__maps_by_address(parent);
        n = maps__nr_maps(parent);
-       if (maps__empty(dest)) {
+       if (maps__nr_maps(dest) == 0) {
                /* No existing mappings so just copy from parent to avoid reallocs in insert. */
                unsigned int nr_maps_allocated = RC_CHK_ACCESS(parent)->nr_maps_allocated;
                struct map **dest_maps_by_address =

diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
index 4bcba13..d9aa62e 100644 (file)
--- a/tools/perf/util/maps.h
+++ b/tools/perf/util/maps.h
@@ -43,8 +43,8 @@ int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data)
 void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data);
 
 struct machine *maps__machine(const struct maps *maps);
-unsigned int maps__nr_maps(const struct maps *maps);
-refcount_t *maps__refcnt(struct maps *maps);
+unsigned int maps__nr_maps(const struct maps *maps); /* Test only. */
+refcount_t *maps__refcnt(struct maps *maps); /* Test only. */
 
 #ifdef HAVE_LIBUNWIND_SUPPORT
 void *maps__addr_space(const struct maps *maps);