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    SubjectRe: [PATCH 2.6.31-rc4] gigaset: really fix chars_in_buffer
    Hi Alan,

    thanks a lot for getting in contact with me, and for your
    explanation of the rationale behind your patch.

    On Sat, 1 Aug 2009 17:11:41 +0100, Alan Cox wrote:
    > Is that correct. If you take a signal so the mutex_lock_interruptible
    > takes the error path we'll exit any waits for characters to be flushed
    > from buffers and lose the bytes in some cases ?

    You are right. I'll have to change it to use non-interruptible
    mutex_lock. I'll prepare a new patch.

    > Thats why I didn't
    > convert it - I didn't understand why it was using _interruptible at all ?

    No specific reason. just the general rule to prefer sleeping
    interuptibly whenever possible, because unkillable processes are
    so annoying. Seeing that chars_in_buffer was declared as returning
    int, I assumed (wrongly as it now turns out) that it would be
    allowed to return the customary negative values for errors, so
    that it could use the _interruptible variant. When I saw your
    patch I read into it that zero would be the appropriate return
    value for all error cases, including a signal while waiting for
    the mutex. I guess there was a bit of wishful thinking in that.

    Well, thanks again for your help. I'll follow up with a revised


    Tilman Schmidt E-Mail:
    Bonn, Germany
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