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    SubjectRe: Who changed /proc/<pid>/ in 2.6.0-test5-bk9?
    Date
    In article <Pine.LNX.4.44.0310010803530.23860-100000@home.osdl.org>,
    Linus Torvalds <torvalds@osdl.org> wrote:
    |
    | On Wed, 1 Oct 2003, Mikael Pettersson wrote:
    | >
    | > Linus' 2.6.0-test6 announcement doesn't seem to mention the
    | > fact that 2.6.0-test5-bk9 fundamentally changed the semantics
    | > of /proc/self and the /proc/<pid> name space.
    |
    | Well, that's because the semantics weren't _supposed_ to change. The new
    | semantics were meant to be a superset of the old behaviour, with just the
    | added "task" subdirectory that lists the actual threads.
    |
    | However, you're right that "/proc/self" should likely point into the
    | _thread_, and not into the task. But it's debatable. You are very likely
    | the only one who could ever care ;)

    Well, it's a subtle detail, and it would be well to document such. He
    may be the only person to use that, but it's certainly not intuitive,
    and if I were to ever do this I'm certainly alerted that it might
    violate Plauger's law of least astonishment. I would hope it points to
    the thread, but if it doesn't it's not something I use every day ;-)
    |
    | > I don't actually disagree with the change, but it took me by
    | > surprise since neither the 2.6.0-test6 annoucement nor the
    | > diff between the t5-bk8 and t5-bk9 logs seem to mention it.
    |
    | Well, the changelog mentions "fix for hidden task problem", since the diff
    | really is mainly to _add_ threads to the /proc layout. The fact that it
    | changed /proc/self is actually a bit surprising. Albert?

    When I get this one built I'm going to see which getpid() (and family)
    returns as well, I never though of using /proc/self from a thread, but
    I do on rare occasions get my pid.
    |
    | > (It broke the perfctr driver, but I'm handling that by making
    | > an already planned API switch now instead of later.)
    |
    | I think /proc/self most likely _should_ point into the thread, not the
    | task.

    Hopefully that was an unintended side effect.
    --
    bill davidsen <davidsen@tmr.com>
    CTO, TMR Associates, Inc
    Doing interesting things with little computers since 1979.
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