On Thu, 30 Sep 2010 09:53:09 +0200 Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> Le jeudi 30 septembre 2010 __ 07:36 +0200, Eric Dumazet a __crit :
> > Le mercredi 29 septembre 2010 __ 21:53 -0700, Andrew Morton a __crit :
>
> > > > +static unsigned int last_ino_get(void)
> > > > +{
> > > > + static unsigned int last_ino;
> > > > +
> > > > + return ++last_ino;
> > > > +}
> > >
> > > This is racy with CONFIG_PREEMPT on some architectures, I suspect. I'd
> > > suggest conversion to atomic_t with, of course, an explanatory comment ;)
> > >
> >
>
> In fact this code was OK when I submitted my original patch back in
> 2008, since it replaced fs/inode.c
>
> inode->i_ino = ++last_ino;
>
> And this was protected by a surrounding spinlock
> (spin_lock(&inode_lock); at that time)
>
> Even after Nick patches, preemption is still disabled (by two
> spinlocks... spin_lock(&sb_inode_list_lock); /
> spin_lock(&inode->i_lock);)
You know, if it took you and me this long to work that out then perhaps
the code isn't quite as clear as we would like it to be, no?
I think you know what's coming next ;)
As a general rule, if a reviewer's comment doesn't result in a code
change then it should result in a changelog fix or a code comment.
Because if the code wasn't clear enough to the reviewer then it won't be
clear enough to later readers.
> So patch 15/17 seems good to me, I re-sign it as-is ;)
>
> Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
>
> If it happens preemption is re-enabled later (with future patches), we
> might need to change last_ino_get() too.
Perhaps
WARN_ON_ONCE(preemptible());
if we had a developer-only version of WARN_ON_ONCE, which we don't.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
