(2010/11/18 17:28), Philipp Hahn wrote: > Hello, > > Am Donnerstag 18 November 2010 01:41:39 schrieb Hidetoshi Seto: >> This patch introduce a fallback mechanism for old systems that do not >> support utimensat(). This fix build failure with following warnings: > >> +#ifdef CONFIG_UTIMENSAT >> + return utimensat(dirfd, path, times, flags); >> +#else >> + /* Fallback: use utimes() instead of utimensat() */ > > Since we also had a problem with utimestat() some time ago with Samba > <http://lists.samba.org/archive/samba-technical/2010-November/074613.html> > I'd like to comment on that: > > Your have to be careful about compile-time-detection and runtime-detection: If > you later run your utimestat()-enabled binary on an older kernel not > supporting that syscall, you get -1 as the return-value and errno=ENOSYS. So > even if you detected utimesatat() during compile-time, please always provide > a fallback for run-time. > This is less important for people compiling there own version of kvm, but is > essential for Linux distributions, since people often run newer kvm versions > on older kernels. Hum, you have a good point. Well, then I'll change it like: -#ifdef CONFIG_UTIMENSAT - return utimensat(dirfd, path, times, flags); -#else + { + int ret = utimensat(dirfd, path, times, flags); + if (ret != -1 || errno != ENOSYS) { + return ret; + } + } Thanks, H.Seto -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
