lkml.org 
[lkml]   [2005]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: patch to fix set_itimer() behaviour in boundary cases
    From
    Date
    On Sat, 2005-01-15 at 01:36 -0800, William Lee Irwin III wrote:
    > Matthias Lang <matthias@corelatus.se> wrote:
    > >> The linux implementation of setitimer() doesn't behave quite as
    > >> expected. I found several problems:
    > >> 1. POSIX says that negative times should cause setitimer() to
    > >> return -1 and set errno to EINVAL. In linux, the call succeeds.
    > >> 2. POSIX says that time values with usec >= 1000000 should
    > >> cause the same behaviour. In linux, the call succeeds.
    > >> 3. If large time values are given, linux quietly truncates them
    > >> to the maximum time representable in jiffies. On 2.4.4 on PPC,
    > >> that's about 248 days. On 2.6.10 on x86, that's about 24 days.
    > >> POSIX doesn't really say what to do in this case, but looking at
    > >> established practice, i.e. "what BSD does", since the call comes
    > >> from BSD, *BSD returns -1 if the time is out of range.
    >
    > On Sat, Jan 15, 2005 at 01:30:13AM -0800, Andrew Morton wrote:
    > > These are things we probably cannot change now. All three are arguably
    > > sensible behaviour and do satisfy the principle of least surprise. So
    > > there may be apps out there which will break if we "fix" these things.
    > > If the kernel version was 2.7.0 then well maybe...
    >
    > We can easily do a "rolling upgrade" by adding new versions of the
    > system calls, giving glibc and apps grace periods to adjust to them,
    > and nuking the old versions in a few years.

    but for 1: do we care? it is being more tolerant than allowed by a
    standard. Those who care can easily add the test in the userspace
    wrapper

    for 2: we again are more tolerant and dtrt; again. And again userspace
    wrapper can impose an additional restriction if it wants

    3 is more nasty and needs thinking; we could consider a fix inside the
    kernel that actually does wait long enough


    I don't see a valid reason to restrict/reject input that is accepted now
    and dealt with reasonably because some standard says so (if you design a
    new api, following the standard is nice of course). I don't see "doesn't
    reject a condition that can reasonable be dealt with" as a good reason
    to go double ABI at all.


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:09    [W:0.030 / U:63.496 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site