[PATCH v2 2/2] selftest: improve mmap test clarity

[Suresh K C <suresh.k.chandrappa@gmail.com>]

From: Suresh K C <suresh.k.chandrappa@gmail.com>

This patch refactors the mmap test logic to remove redundancy and improve
error reporting. It also removes leftover test code that is no longer needed.

Changes since v1:
- Refactored mmap logic into a switch statement as suggested
- Removed the last-character difference, which was only used for testing
- Added clearer error messages to indicate whether shmem or mmap failed
- Combined patches into a series for better context
- Addressed feedback on patch origin and versioning

Signed-off-by: Suresh K C <suresh.k.chandrappa@gmail.com>
---
 .../selftests/cachestat/test_cachestat.c      | 52 +++++++++++++------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c
index b6452978dae0..0549b7224ba1 100644
--- a/tools/testing/selftests/cachestat/test_cachestat.c
+++ b/tools/testing/selftests/cachestat/test_cachestat.c
@@ -206,6 +206,17 @@ static int test_cachestat(const char *filename, bool write_random, bool create,
 out:
 	return ret;
 }
+const char* file_type_str(enum file_type type) {
+	switch (type) {
+		case FILE_SHMEM:
+			return "shmem";
+		case FILE_MMAP:
+			return "mmap";
+		default:
+			return "unknown";
+	}
+}
+
 
 bool run_cachestat_test(enum file_type type)
 {
@@ -225,34 +236,41 @@ bool run_cachestat_test(enum file_type type)
 		fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);
 
 	if (fd < 0) {
-		ksft_print_msg("Unable to create file.\n");
+		ksft_print_msg("Unable to create %s file.\n",file_type_str(type));
 		ret = false;
 		goto out;
 	}
 
 	if (ftruncate(fd, filesize)) {
-		ksft_print_msg("Unable to truncate file.\n");
-		ret = false;
-		goto close_fd;
-	}
-
-	if (!write_exactly(fd, filesize)) {
-		ksft_print_msg("Unable to write to file.\n");
+		ksft_print_msg("Unable to truncate %s file.\n",file_type_str(type));
 		ret = false;
 		goto close_fd;
 	}
 
-	if (type == FILE_MMAP){
-		char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-		if (map == MAP_FAILED) {
-			ksft_print_msg("mmap failed.\n");
+	switch (type){
+		case FILE_SHMEM:
+			if (!write_exactly(fd, filesize)) {
+				ksft_print_msg("Unable to write to file.\n");
+				ret = false;
+				goto close_fd;
+			}
+			break;
+		case FILE_MMAP:
+			char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+			if (map == MAP_FAILED) {
+				ksft_print_msg("mmap failed.\n");
+				ret = false;
+				goto close_fd;
+			}
+			for (int i = 0; i < filesize; i++) {
+				map[i] = 'A';
+			}
+			break;
+		default:
+			ksft_print_msg("Unsupported file type.\n");
 			ret = false;
 			goto close_fd;
-		}
-		for (int i = 0; i < filesize; i++) {
-			map[i] = 'A';
-		}
-		map[filesize - 1] = 'X';
+			break;
 	}
 	syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);
 
-- 
2.43.0