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SubjectRe: [PATCH 12/25] aio: Refcounting cleanup

> 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?

> + 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.

> + 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?

- z


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