perf ftrace: Fix hashmap__new() error checking

The hashmap__new() function never returns NULL, it returns error
pointers. Fix the error checking to match.

Additionally, set ftrace->profile_hash to NULL on error, and return the
exact error code from hashmap__new().

Fixes: 0f22381 ("perf ftrace: Add 'profile' command")
Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: Chen Ni

tools/perf/builtin-ftrace.c

@@ -18,6 +18,7 @@
 #include <poll.h>
 #include <ctype.h>
 #include <linux/capability.h>
+#include <linux/err.h>
 #include <linux/string.h>
 #include <sys/stat.h>
 
@@ -1209,8 +1210,12 @@ static int prepare_func_profile(struct perf_ftrace *ftrace)
 	ftrace->graph_verbose = 0;
 
 	ftrace->profile_hash = hashmap__new(profile_hash, profile_equal, NULL);
-	if (ftrace->profile_hash == NULL)
-		return -ENOMEM;
+	if (IS_ERR(ftrace->profile_hash)) {
+		int err = PTR_ERR(ftrace->profile_hash);
+
+		ftrace->profile_hash = NULL;
+		return err;
+	}
 
 	return 0;
 }