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    SubjectRe: [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos
    On Mon, 18 Jan 2010 10:32:49 +0900
    OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> wrote:

    > OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> writes:
    >
    > >>> Um... How do lseek() work? It sounds like to violate error code range.
    > >>
    > >> This is for read-write. As far as I know,
    > >> - generic_file_llseek,
    > >> - default_llseek
    > >> - no_llseek
    > >>
    > >> doesn't call this function.
    > >
    > > It seems to allow to set negative value to ->f_pos, right? So, lseek()
    > > returns (uses) it?
    >
    > BTW, another concern by negative "pos" value is, the following like code
    >
    > pos >> shift_bits
    >
    > it will break the above. So, I think it should be checked if not yet.

    Where do we check ?

    FMODE_NEG_OFFSET is just used by /dev/mem and /proc/<pid>/mem. And I don't
    think there are no additonal users. So, I myself don't have has such concerns...


    Thanks,
    -Kame



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