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    SubjectRe: light weight user level semaphores
    On Thu, Apr 19, 2001 at 09:46:17AM -0700, Linus Torvalds wrote:
    > > libc is entitled to, and most definitely does exactly that. Take a look at
    > > things like gethostent, getpwent etc etc.
    > Ehh.. I will bet you $10 USD that if libc allocates the next file
    > descriptor on the first "malloc()" in user space (in order to use the
    > semaphores for mm protection), programs _will_ break.

    But we would not open the semaphore on malloc() but instead in
    the init functions of the libc. So the semaphore will be already
    allocated. May be dup2()ed to some very high range
    (INT_MAX-__GLIBC_MALLOC_SEM_FD) and the original fd closed.

    So this will be no real problem. That's why I don't like lazy
    init: May be you cannot init anymore, if you come to and
    condition, where you would need it.

    Also init/fini are usally very slow operations and as many things
    as possible are burdend onto their shoulders.

    Semaphores tend to be structures living very long (at least in
    all code I've written and seen so far) so I see no point in
    defering their initialization.


    Ingo Oeser
    10.+11.03.2001 - 3. Chemnitzer LinuxTag <>
    <<<<<<<<<<<< been there and had much fun >>>>>>>>>>>>
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