On Wed, Nov 28, 2012 at 04:17:59PM -0800, Zach Brown wrote:
>
> > struct kioctx {
> > atomic_t users;
> > - int dead;
> > + atomic_t dead;
>
> Do we want to be paranoid and atomic_set() that to 0 when the ioctx is
> allocated?
I suppose we should, yeah.
> > + while (!list_empty(&ctx->active_reqs)) {
> > + struct list_head *pos = ctx->active_reqs.next;
> > + struct kiocb *iocb = list_kiocb(pos);
>
> I'd use list_first_entry() and ignore the list_kiocb() wrapper, I think.
Fine by me.
>
> > + if (!atomic_xchg(&ctx->dead, 1)) {
> > + hlist_del_rcu(&ctx->list);
> > + synchronize_rcu();
>
> > + hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list)
> > + if (ctx->user_id == ctx_id){
> > + BUG_ON(atomic_read(&ctx->dead));
>
> Hmm. Won't it be possible to race lookup and io_destroy() to hit this
> BUG?
Ouch, yes. Dunno what I was thinking when I added that.
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