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    SubjectRe: [PATCH 16/18] llseek: automatically add .llseek fop
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    On Wednesday 07 July 2010 23:55:25 Mike Frysinger wrote:
    > > New drivers should normally not use
    > > noop_llseek but instead use no_llseek and
    > > call nonseekable_open at open time.
    > > Existing drivers can be converted to do
    > > the same when the maintainer knows for
    > > certain that no user code relies on calling
    > > seek on the device file.
    >
    > can we skip the transition for devices that we already know ?

    Yes, we could do that for the cases that call nonseekable_open
    either by putting it into file_operations or by calling it
    from their own open() function in the same file. These
    are the two cases where the semantic patch currently adds
    no_llseek.

    The reason I added the explicit no_llseek was so I could
    tell the difference between those file operations that
    use nonseekable_open and those that spatch could for
    some reason not identify as belonging into any of the
    categories.

    > > --- a/arch/blackfin/kernel/kgdb_test.c
    > > +++ b/arch/blackfin/kernel/kgdb_test.c
    > > static const struct file_operations kgdb_test_proc_fops = {
    > > + .llseek = noop_llseek,/* read and write both use no f_pos */
    > > --- a/arch/blackfin/mach-bf561/coreb.c
    > > +++ b/arch/blackfin/mach-bf561/coreb.c
    > > static const struct file_operations coreb_fops = {
    > > + .llseek = noop_llseek,/* no read or write fn */
    >
    > neither of these drivers are seekable, so attempts to do so should be
    > an error ...

    Ok, then you should add ".open = nonseekable_open," to the file
    operations and put that change into a tree that gets pulled into
    linux-next. The semantic patch will do the right thing then,
    whatever we decide.

    Arnd


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