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    SubjectRe: [PATCH 6/9] isdn4linux: Siemens Gigaset drivers - procfs interface

    thank you very much for your comments.

    On 12.02.2006 11:27, Andrew Morton wrote:
    >>This patch adds the procfs interface to the gigaset module.
    > sysfs, actually.

    Yes, sorry, the comment didn't get updated when we did the move from
    procfs to sysfs.

    > - The ringbuffer head and tail indexes are atomic_t's, but always seem to
    > be manipulated inside the lock. Perhaps they can become integers.

    We use ringbuffers in two places. I suppose you are talking about the
    one implementing our event queue through the ev_head and ev_tail members
    of the cardstate structure. You have a point there, although I'm not
    sure if it wouldn't be better to take advantage of the atomic_t and do a
    little less locking instead.

    The other one, within the inbuf_t structure, used for capturing
    characters received from the device, is accessed without locking from
    the gigaset_handle_event() tasklet and therefore needs atomic_t indexes,

    > - You did the ringbuffer the wrong way. Don't constrain the head and
    > tail to be within 0..MAX_EVENTS. Instead, just let them wrap right up to
    > 0xffffffff. Apply the masking when you actually _use_ them.
    > That way, empty is (head == tail) and full is (tail - head == MAX_EVENTS).

    Interesting idea. I have to admit it's rather new to me. I have always
    done ringbuffers the way they are done in the Gigaset driver now. Can
    you point me to some example code done the way you propose, so I can
    familiarize myself with its advantages?

    > - Could use kstrdup() in a few places.

    Thanks for the hint. Will watch out for these.

    > - A few unneeded casts of void*'s, but everyone does that.


    > - There are a lot of global symbols in there. Perhaps they don't all
    > need to be global.

    Well, I *hope* there aren't any unnecessary ones, but we'll re-check.


    Tilman Schmidt E-Mail:
    Bonn, Germany
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