perf trace: Avoid an ERR_PTR in syscall_stats

[ Upstream commit d05073a ]

hashmap__new may return an ERR_PTR and previously this would be
assigned to syscall_stats meaning all use of syscall_stats needs to
test for NULL (uninitialized) or an ERR_PTR. Given the only reason
hashmap__new can fail is ENOMEM, just use NULL to indicate the
allocation failure and avoid the code having to test for NULL and
IS_ERR.

Fixes: 96f202e (perf trace: Fix IS_ERR() vs NULL check bug)
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: captain5050

tools/perf/builtin-trace.c

@@ -1565,15 +1565,17 @@ static bool syscall_id_equal(long key1, long key2, void *ctx __maybe_unused)
 
 static struct hashmap *alloc_syscall_stats(void)
 {
-	return hashmap__new(syscall_id_hash, syscall_id_equal, NULL);
+	struct hashmap *result = hashmap__new(syscall_id_hash, syscall_id_equal, NULL);
+
+	return IS_ERR(result) ? NULL : result;
 }
 
 static void delete_syscall_stats(struct hashmap *syscall_stats)
 {
 	struct hashmap_entry *pos;
 	size_t bkt;
 
-	if (IS_ERR(syscall_stats))
+	if (!syscall_stats)
 		return;
 
 	hashmap__for_each_entry(syscall_stats, pos, bkt)
@@ -1589,7 +1591,7 @@ static struct thread_trace *thread_trace__new(struct trace *trace)
 		ttrace->files.max = -1;
 		if (trace->summary) {
 			ttrace->syscall_stats = alloc_syscall_stats();
-			if (IS_ERR(ttrace->syscall_stats))
+			if (!ttrace->syscall_stats)
 				zfree(&ttrace);
 		}
 	}
@@ -4441,7 +4443,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 
 	if (trace->summary_mode == SUMMARY__BY_TOTAL && !trace->summary_bpf) {
 		trace->syscall_stats = alloc_syscall_stats();
-		if (IS_ERR(trace->syscall_stats))
+		if (!trace->syscall_stats)
 			goto out_delete_evlist;
 	}
 
@@ -4749,7 +4751,7 @@ static int trace__replay(struct trace *trace)
 
 	if (trace->summary_mode == SUMMARY__BY_TOTAL) {
 		trace->syscall_stats = alloc_syscall_stats();
-		if (IS_ERR(trace->syscall_stats))
+		if (!trace->syscall_stats)
 			goto out;
 	}