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    SubjectRe: [PATCH 2/4] set_restore_sigmask TIF_SIGPENDING
    Roland, Linus, I'm sorry for being offtopic, but there is something
    I can't understand from the very beginning, when TIF_RESTORE_SIGMASK
    was introduced.

    On 03/28, Linus Torvalds wrote:
    >
    > On Fri, 28 Mar 2008, Roland McGrath wrote:
    > >
    > > Set TIF_SIGPENDING in set_restore_sigmask. This lets arch code take
    > > TIF_RESTORE_SIGMASK out of the set of bits that will be noticed on
    > > return to user mode. On some machines those bits are scarce, and we
    > > can free this unneeded one up for other uses.
    >
    > Hmm. That probably means that TIF_RESTORE_SIGMASK shouldn't be a "TIF"
    > flag at all,

    Yes!

    > but a "TS" ("thread status") flag.

    Why do we need any flag? It looks a bit ugly. Isn't it better to introduce
    the new magic ERESTART_XXX which means ERESTARTNOHAND + restore-sigmask ?

    We only need this flag as an implicit parameter to the arch dependent do_signal()
    which we can't call directly, and thus it must imply TIF_SIGPENDING, and it
    is not valid after do_signal() (should be cleared). This all looks like
    ERESTART_ magic, why should we add something else ?

    See also http://marc.info/?l=linux-kernel&m=113734458516136

    Of course, probably it is too late to change the implementation even if
    I am right, the question is: what I am missed?

    Oleg.



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