Update write() checks to properly detect and handle partial writes. Previously, partial writes (ret > 0 && ret != len) would return -errno, but write() does not set errno in this case. This could result in returning 0 and incorrectly signaling success.
Fix this by: - returning -errno only on actual failures (ret < 0) - returning -EIO when a partial write is detected This ensures partial writes are treated as errors and prevents false success reporting in tests. Signed-off-by: Vineet Agarwal <[email protected]> Changes in v2: - Fix incorrect use of -errno on partial writes - Return -EIO when write() completes partially --- tools/testing/selftests/mm/ksm_functional_tests.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c index 9a8c852acd68..c80254cda926 100644 --- a/tools/testing/selftests/mm/ksm_functional_tests.c +++ b/tools/testing/selftests/mm/ksm_functional_tests.c @@ -507,9 +507,13 @@ static int start_ksmd_and_set_frequency(char *pages_to_scan, char *sleep_ms) if (write(ksm_fd, "1", 1) != 1) return -errno; - ret = write(pages_to_scan_fd, pages_to_scan, strlen(pages_to_scan)); - if (ret < 0 || ret != strlen(pages_to_scan)) + ssize_t len = strlen(pages_to_scan); + + ret = write(pages_to_scan_fd, pages_to_scan, len); + if (ret < 0) return -errno; + if (ret != len) + return -EIO; ret = write(sleep_millisecs_fd, sleep_ms, strlen(sleep_ms)); if (ret < 0 || ret != strlen(sleep_ms)) @@ -531,8 +535,10 @@ static int stop_ksmd_and_restore_frequency(void) return -errno; ret = write(pages_to_scan_fd, "100", 3); - if (ret < 0 || ret != 3) + if (ret < 0) return -errno; + if (ret != 3) + return -EIO; ret = write(sleep_millisecs_fd, "20", 2); if (ret < 0 || ret != 2) -- 2.54.0
