Just reporting failure doesn't tell you what went wrong. This can fail
in different ways so report errno to help the reader get started
debugging.

Reviewed-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 tools/testing/selftests/mm/gup_longterm.c | 37 ++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
index 9423ad439a6140163bdef2974615bb86406a8c14..15335820656b1c143b440b8a1065a025378e22a2 100644
--- a/tools/testing/selftests/mm/gup_longterm.c
+++ b/tools/testing/selftests/mm/gup_longterm.c
@@ -96,13 +96,13 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 	int ret;
 
 	if (ftruncate(fd, size)) {
-		ksft_test_result_fail("ftruncate() failed\n");
+		ksft_test_result_fail("ftruncate() failed (%s)\n", strerror(errno));
 		return;
 	}
 
 	if (fallocate(fd, 0, 0, size)) {
 		if (size == pagesize)
-			ksft_test_result_fail("fallocate() failed\n");
+			ksft_test_result_fail("fallocate() failed (%s)\n", strerror(errno));
 		else
 			ksft_test_result_skip("need more free huge pages\n");
 		return;
@@ -112,7 +112,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 		   shared ? MAP_SHARED : MAP_PRIVATE, fd, 0);
 	if (mem == MAP_FAILED) {
 		if (size == pagesize || shared)
-			ksft_test_result_fail("mmap() failed\n");
+			ksft_test_result_fail("mmap() failed (%s)\n", strerror(errno));
 		else
 			ksft_test_result_skip("need more free huge pages\n");
 		return;
@@ -130,7 +130,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 		 */
 		ret = mprotect(mem, size, PROT_READ);
 		if (ret) {
-			ksft_test_result_fail("mprotect() failed\n");
+			ksft_test_result_fail("mprotect() failed (%s)\n", strerror(errno));
 			goto munmap;
 		}
 		/* FALLTHROUGH */
@@ -165,18 +165,20 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 		args.flags |= rw ? PIN_LONGTERM_TEST_FLAG_USE_WRITE : 0;
 		ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
 		if (ret && errno == EINVAL) {
-			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
+			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed (EINVAL)n");
 			break;
 		} else if (ret && errno == EFAULT) {
 			ksft_test_result(!should_work, "Should have failed\n");
 			break;
 		} else if (ret) {
-			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
+			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed (%s)\n",
+					      strerror(errno));
 			break;
 		}
 
 		if (ioctl(gup_fd, PIN_LONGTERM_TEST_STOP))
-			ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
+			ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed (%s)\n",
+				       strerror(errno));
 
 		/*
 		 * TODO: if the kernel ever supports long-term R/W pinning on
@@ -202,7 +204,8 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 		/* Skip on errors, as we might just lack kernel support. */
 		ret = io_uring_queue_init(1, &ring, 0);
 		if (ret < 0) {
-			ksft_test_result_skip("io_uring_queue_init() failed\n");
+			ksft_test_result_skip("io_uring_queue_init() failed (%s)\n",
+					      strerror(-ret));
 			break;
 		}
 		/*
@@ -215,13 +218,15 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
 		/* Only new kernels return EFAULT. */
 		if (ret && (errno == ENOSPC || errno == EOPNOTSUPP ||
 			    errno == EFAULT)) {
-			ksft_test_result(!should_work, "Should have failed\n");
+			ksft_test_result(!should_work, "Should have failed (%s)\n",
+					 strerror(errno));
 		} else if (ret) {
 			/*
 			 * We might just lack support or have insufficient
 			 * MEMLOCK limits.
 			 */
-			ksft_test_result_skip("io_uring_register_buffers() failed\n");
+			ksft_test_result_skip("io_uring_register_buffers() failed (%s)\n",
+					      strerror(-ret));
 		} else {
 			ksft_test_result(should_work, "Should have worked\n");
 			io_uring_unregister_buffers(&ring);
@@ -249,7 +254,7 @@ static void run_with_memfd(test_fn fn, const char *desc)
 
 	fd = memfd_create("test", 0);
 	if (fd < 0) {
-		ksft_test_result_fail("memfd_create() failed\n");
+		ksft_test_result_fail("memfd_create() failed (%s)\n", strerror(errno));
 		return;
 	}
 
@@ -266,13 +271,13 @@ static void run_with_tmpfile(test_fn fn, const char *desc)
 
 	file = tmpfile();
 	if (!file) {
-		ksft_test_result_fail("tmpfile() failed\n");
+		ksft_test_result_fail("tmpfile() failed (%s)\n", strerror(errno));
 		return;
 	}
 
 	fd = fileno(file);
 	if (fd < 0) {
-		ksft_test_result_fail("fileno() failed\n");
+		ksft_test_result_fail("fileno() failed (%s)\n", strerror(errno));
 		goto close;
 	}
 
@@ -290,12 +295,12 @@ static void run_with_local_tmpfile(test_fn fn, const char *desc)
 
 	fd = mkstemp(filename);
 	if (fd < 0) {
-		ksft_test_result_fail("mkstemp() failed\n");
+		ksft_test_result_fail("mkstemp() failed (%s)\n", strerror(errno));
 		return;
 	}
 
 	if (unlink(filename)) {
-		ksft_test_result_fail("unlink() failed\n");
+		ksft_test_result_fail("unlink() failed (%s)\n", strerror(errno));
 		goto close;
 	}
 
@@ -317,7 +322,7 @@ static void run_with_memfd_hugetlb(test_fn fn, const char *desc,
 
 	fd = memfd_create("test", flags);
 	if (fd < 0) {
-		ksft_test_result_skip("memfd_create() failed\n");
+		ksft_test_result_skip("memfd_create() failed (%s)\n", strerror(errno));
 		return;
 	}
 

-- 
2.49.0.rc0.332.g42c0ae87b1-goog