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SubjectRe: [PATCH] macintosh: Explicitly set llseek to no_llseek in ans-lcd


On Wed, 21 Oct 2009, Frederic Weisbecker wrote:

> On Wed, Oct 21, 2009 at 11:07:18PM +0200, John Kacur wrote:
> > From 0c2b412cdccf73bdeb19bb866bfe556942eaeca2 Mon Sep 17 00:00:00 2001
> > From: John Kacur <jkacur@redhat.com>
> > Date: Wed, 21 Oct 2009 23:01:12 +0200
> > Subject: [PATCH] macintosh: Explicitly set llseek to no_llseek in ans-lcd
> >
> > Now that we've removed the BKL here, let's explicitly set lleek to no_llseek
> >
> > Signed-off-by: John Kacur <jkacur@redhat.com>
> > ---
> > drivers/macintosh/ans-lcd.c | 1 +
> > 1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/macintosh/ans-lcd.c b/drivers/macintosh/ans-lcd.c
> > index 4ae8ec9..a1a1bde 100644
> > --- a/drivers/macintosh/ans-lcd.c
> > +++ b/drivers/macintosh/ans-lcd.c
> > @@ -137,6 +137,7 @@ const struct file_operations anslcd_fops = {
> > .write = anslcd_write,
> > .unlocked_ioctl = anslcd_ioctl,
> > .open = anslcd_open,
> > + .llseedk = no_llseek,
>
>
> llseedk? :)
>
>
> Should we better pushdown default_llseek to every to every
> file operations that don't implement llseek?
> I don't know how many of them don't implement llseek() though.
>
> That said we can't continue anymore with this default attribution
> of default_llseek() on new fops.
>

If you don't explicitly set it to no_llseek, you automatically get the
default_llseek, which uses the BKL. So if your driver doesn't need it, it
is best to explicitly set it to no_llseek.

There is also a generic_file_llseek_unlocked, somewhat analogous to the
unlocked_ioctls that you can use if you don't need to provide a full
llseek yourself.


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