Re: [PATCH v2 5/7][next] printk: ringbuffer: add finalization/extension support

[John Ogness <john.ogness@linutronix.de>]

On 2020-08-24, John Ogness <john.ogness@linutronix.de> wrote:
> @@ -1157,6 +1431,14 @@ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb,
>  		goto fail;
>  	}
>  
> +	/*
> +	 * New data is about to be reserved. Once that happens, previous
> +	 * descriptors are no longer able to be extended. Finalize the
> +	 * previous descriptor now so that it can be made available to
> +	 * readers (when committed).
> +	 */
> +	desc_finalize(desc_ring, DESC_ID(id - 1));
> +
>  	d = to_desc(desc_ring, id);
>  
>  	/*

Apparently this is not enough to guarantee that past descriptors are
finalized. I am able to reproduce a scenario where the finalization of a
certain descriptor never happens. That leaves the descriptor permanently
in the reserved queried state, which prevents any new records from being
created. I am investigating.

John Ogness