On Sun, May 03, 2026 at 11:30:30AM +0530, Vineet Agarwal wrote: > 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
Please start a new thread for a new version of the patch. > --- > 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); The v2 diff should be against the base, not against v1. > + > + ret = write(pages_to_scan_fd, pages_to_scan, len); > + if (ret < 0) > return -errno; > + if (ret != len) > + return -EIO; Just return -1 if write() != strlen(), the actual error code does not matter anyway. > 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 > -- Sincerely yours, Mike.
