On Sun, 20 May 2007 22:05:00 -0700 (PDT) Davide Libenzi <[EMAIL PROTECTED]> wrote:
> On Sun, 20 May 2007, Andrew Morton wrote: > > > > I think it fits the rule "buffer must be big enough for at least one > > > sigingo". > > > We use the special return 0; as indicator that the process we were > > > monitoring signals, detached the sighand. > > > > > > > hm. Kernel violates proper read() semantics in many places. Looks like we > > just did it again. > > I think we can have the check that "if size == 0 return 0". The above > cited return-0-on-detch would still apply for enough sized buffers. So: > > 1) size == 0, return 0 (POSIX wants this) > > 2) size < sizeof(signalfd_siginfo), return EINVAL > > 3) size >= sizeof(signalfd_siginfo) && DETACH, return 0 > > The signalfd falls into what POSIX defined as "special file", and can > return a lower-than-size result. > hm, well. I'd suggest that we do what makes most sense, rather than warping things to try to obey the letter of posix. > > > Unless we just remove the __clear_user() altogether. Who said that "Unused > > memebers should be zero"? > > Because it is a typically used value for still-unused/reserved members? > Better than random values I think ;) > Members validity is driven by si_code & SI_MASK anyway. Sure. And it'd be a bit rude to return 128 from the read() but to only have written to a few bytes of the user's memory. otoh, only-writing-a-few-bytes will be usefully quicker than zapping the whole 128b, particularly on small-cacheline CPUs. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
