[PATCH v3] perf expr: Fix return value of ids__new

[Miaoqian Lin <linmq006@gmail.com>]

callers of ids__new() function only do NULL checking for the return
value. ids__new() calles hashmap__new(), which may return
ERR_PTR(-ENOMEM). Instead of changing the checking one-by-one.
return NULL instead of ERR_PTR(-ENOMEM) to keep
consistent.

---
Changes in v3:
fix compilation error and add tags.
---
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Tested-by: German Gomez <german.gomez@arm.com>
Reviewed-by: German Gomez <german.gomez@arm.com>
---
 tools/perf/util/expr.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 1d532b9fed29..f225247acc01 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -12,6 +12,7 @@
 #include "expr-bison.h"
 #include "expr-flex.h"
 #include "smt.h"
+#include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/zalloc.h>
 #include <ctype.h>
@@ -65,7 +66,12 @@ static bool key_equal(const void *key1, const void *key2,
 
 struct hashmap *ids__new(void)
 {
-	return hashmap__new(key_hash, key_equal, NULL);
+	struct hashmap *hash;
+
+	hash = hashmap__new(key_hash, key_equal, NULL);
+	if (IS_ERR(hash))
+		return NULL;
+	return hash;
 }
 
 void ids__free(struct hashmap *ids)
-- 
2.17.1