On Mon, Mar 23, 2026 at 03:39:41PM -0700, Andrew Morton wrote: > On Mon, 23 Mar 2026 23:17:51 +0800 Chunyu Hu <[email protected]> wrote: > > > Add two more checks for buflen and numwritten. The buflen should be at > > least one, otherwise the 'buflen - 1' could underflow and cause trouble. > > The numwritten should be equal to 'buflen - 1'. The test will exit if > > any of these conditions aren't met. > > > > Additionally, add more print information when a write failure occurs or > > a truncated write happens, providing clearer diagnostics. > > > > ... > > > > --- a/tools/testing/selftests/mm/vm_util.c > > +++ b/tools/testing/selftests/mm/vm_util.c > > @@ -769,6 +769,8 @@ void write_file(const char *path, const char *buf, > > size_t buflen) > > { > > int fd; > > ssize_t numwritten; > > + if (buflen < 1) > > + ksft_exit_fail_msg("Incorrect buffer len: %zu\n", buflen); > > > > fd = open(path, O_WRONLY); > > if (fd == -1) > > @@ -777,5 +779,9 @@ void write_file(const char *path, const char *buf, > > size_t buflen) > > numwritten = write(fd, buf, buflen - 1); > > close(fd); > > if (numwritten < 1) > > - ksft_exit_fail_msg("Write failed\n"); > > + ksft_exit_fail_msg("%s write(%s) failed: %s\n", path, buf, > > + strerror(errno)); > > AI review > (https://sashiko.dev/#/patchset/[email protected]) > points out that `errno' was overwritten by the close(). Maybe. Or > maybe a successful close() leaves errno alone, dunno.
I'll address this errno part by adding a save and restore before/after the close(). > > Apart from that the comments appear fairly minor. Please lmk if you > think we should proceed as-is. For the other two minor questions about buflen == 1 and non-null buffer, user should know a string buffer need to be '\0' ended. Those are really minor, we can leave as it is. AI's comment on patch 5 should be other topic, and minor. Let's leave as it it. > > (I'm really trying to slow things down now - we have a *lot* of > material and a few weeks of consolidation is needed. But selftests/ > tend to get a pass, for obvious reasons) >
