Re: [PATCH 30/33] block, aio: batch completion for bios/kiocbs

[Theodore Ts'o]

On Thu, Mar 21, 2013 at 09:35:51AM -0700, Kent Overstreet wrote:
> +		if (unlikely(req->ki_eventfd != eventfd)) {
> +			if (eventfd) {
> +				/* Make event visible */
> +				kioctx_ring_unlock(ctx, tail);
> +				ctx = NULL;
> +
> +				eventfd_signal(eventfd, 1);
> +				eventfd_ctx_put(eventfd);
> +			}

I just noticed something else.  There's a ring unlock here().... but
there isn't a matching ring_lock(), or an exit from the function.
Since you've set the ctx to be NULL, then subsequently, aren't we
going to crash at the subseqent kioctx_ring_unlock() below....

> +
> +			eventfd = req->ki_eventfd;
> +			req->ki_eventfd = NULL;
> +		}
> +
> +		if (unlikely(req->ki_ctx != ctx)) {
> +			kioctx_ring_unlock(ctx, tail);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

(Or the kioctx_ring_unlock() at the end of this function after the
while loop terminates.)

						- Ted

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