[PATCH v1 1/3] selftests/mm: factor out detection of hugetlb page sizes into vm_util

[David Hildenbrand <david@redhat.com>]

Let's factor detection out into vm_util, to be reused by a new test.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 tools/testing/selftests/mm/cow.c     | 29 ++--------------------------
 tools/testing/selftests/mm/vm_util.c | 27 ++++++++++++++++++++++++++
 tools/testing/selftests/mm/vm_util.h |  1 +
 3 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index dc9d6fe86028..7f3b620d9cb7 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -14,7 +14,6 @@
 #include <unistd.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <dirent.h>
 #include <assert.h>
 #include <sys/mman.h>
 #include <sys/ioctl.h>
@@ -70,31 +69,6 @@ static void detect_huge_zeropage(void)
 	close(fd);
 }
 
-static void detect_hugetlbsizes(void)
-{
-	DIR *dir = opendir("/sys/kernel/mm/hugepages/");
-
-	if (!dir)
-		return;
-
-	while (nr_hugetlbsizes < ARRAY_SIZE(hugetlbsizes)) {
-		struct dirent *entry = readdir(dir);
-		size_t kb;
-
-		if (!entry)
-			break;
-		if (entry->d_type != DT_DIR)
-			continue;
-		if (sscanf(entry->d_name, "hugepages-%zukB", &kb) != 1)
-			continue;
-		hugetlbsizes[nr_hugetlbsizes] = kb * 1024;
-		nr_hugetlbsizes++;
-		ksft_print_msg("[INFO] detected hugetlb size: %zu KiB\n",
-			       kb);
-	}
-	closedir(dir);
-}
-
 static bool range_is_swapped(void *addr, size_t size)
 {
 	for (; size; addr += pagesize, size -= pagesize)
@@ -1717,7 +1691,8 @@ int main(int argc, char **argv)
 	if (thpsize)
 		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
 			       thpsize / 1024);
-	detect_hugetlbsizes();
+	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
+						    ARRAY_SIZE(hugetlbsizes));
 	detect_huge_zeropage();
 
 	ksft_print_header();
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 9b06a5034808..5cf84d860076 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <string.h>
 #include <fcntl.h>
+#include <dirent.h>
 #include <sys/ioctl.h>
 #include <linux/userfaultfd.h>
 #include <sys/syscall.h>
@@ -198,6 +199,32 @@ unsigned long default_huge_page_size(void)
 	return hps;
 }
 
+int detect_hugetlb_page_sizes(size_t sizes[], int max)
+{
+	DIR *dir = opendir("/sys/kernel/mm/hugepages/");
+	int count = 0;
+
+	if (!dir)
+		return 0;
+
+	while (count < max) {
+		struct dirent *entry = readdir(dir);
+		size_t kb;
+
+		if (!entry)
+			break;
+		if (entry->d_type != DT_DIR)
+			continue;
+		if (sscanf(entry->d_name, "hugepages-%zukB", &kb) != 1)
+			continue;
+		sizes[count++] = kb * 1024;
+		ksft_print_msg("[INFO] detected hugetlb page size: %zu KiB\n",
+			       kb);
+	}
+	closedir(dir);
+	return count;
+}
+
 /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
 int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
 			      bool miss, bool wp, bool minor, uint64_t *ioctls)
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index b950bd16083a..99b795528716 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -44,6 +44,7 @@ bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size);
 bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
 int64_t allocate_transhuge(void *ptr, int pagemap_fd);
 unsigned long default_huge_page_size(void);
+int detect_hugetlb_page_sizes(size_t sizes[], int max);
 
 int uffd_register(int uffd, void *addr, uint64_t len,
 		  bool miss, bool wp, bool minor);
-- 
2.40.1