selftests/mm: map_populate: conform test to TAP format output

Conform the layout, informational and status messages to TAP.  No
functional change is intended other than the layout of output messages. 
Minor cleanups have also been included.

Link: https://lkml.kernel.org/r/20240202113119.2047740-4-usama.anjum@collabora.comSigned-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/map_populate.c

@@ -16,19 +16,21 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include "../kselftest.h"
 
 #define MMAP_SZ		4096
 
-#define BUG_ON(condition, description)					\
-	do {								\
-		if (condition) {					\
-			fprintf(stderr, "[FAIL]\t%s:%d\t%s:%s\n", __func__, \
-				__LINE__, (description), strerror(errno)); \
-			exit(1);					\
-		}							\
+#define BUG_ON(condition, description)						\
+	do {									\
+		if (condition)							\
+			ksft_exit_fail_msg("[FAIL]\t%s:%d\t%s:%s\n",		\
+					   __func__, __LINE__, (description),	\
+					   strerror(errno));			\
 	} while (0)
 
-static int parent_f(int sock, unsigned long *smap, int child)
+#define TESTS_IN_CHILD 2
+
+static void parent_f(int sock, unsigned long *smap, int child)
 {
 	int status, ret;
 
@@ -43,9 +45,10 @@ static int parent_f(int sock, unsigned long *smap, int child)
 	BUG_ON(ret <= 0, "write(sock)");
 
 	waitpid(child, &status, 0);
-	BUG_ON(!WIFEXITED(status), "child in unexpected state");
 
-	return WEXITSTATUS(status);
+	/* The ksft macros don't keep counters between processes */
+	ksft_cnt.ksft_pass = WEXITSTATUS(status);
+	ksft_cnt.ksft_fail = TESTS_IN_CHILD - WEXITSTATUS(status);
 }
 
 static int child_f(int sock, unsigned long *smap, int fd)
@@ -64,10 +67,11 @@ static int child_f(int sock, unsigned long *smap, int fd)
 	ret = read(sock, &buf, sizeof(int));
 	BUG_ON(ret <= 0, "read(sock)");
 
-	BUG_ON(*smap == 0x22222BAD, "MAP_POPULATE didn't COW private page");
-	BUG_ON(*smap != 0xdeadbabe, "mapping was corrupted");
+	ksft_test_result(*smap != 0x22222BAD, "MAP_POPULATE COW private page\n");
+	ksft_test_result(*smap == 0xdeadbabe, "The mapping state\n");
 
-	return 0;
+	/* The ksft macros don't keep counters between processes */
+	return ksft_cnt.ksft_pass;
 }
 
 int main(int argc, char **argv)
@@ -76,6 +80,9 @@ int main(int argc, char **argv)
 	FILE *ftmp;
 	unsigned long *smap;
 
+	ksft_print_header();
+	ksft_set_plan(TESTS_IN_CHILD);
+
 	ftmp = tmpfile();
 	BUG_ON(!ftmp, "tmpfile()");
 
@@ -101,7 +108,9 @@ int main(int argc, char **argv)
 		ret = close(sock[0]);
 		BUG_ON(ret, "close()");
 
-		return parent_f(sock[1], smap, child);
+		parent_f(sock[1], smap, child);
+
+		ksft_finished();
 	}
 
 	ret = close(sock[1]);