Re: [PATCH v5 04/12] nvmet-fc: defer cleanup using RCU properly

[Hannes Reinecke]

On 1/31/24 09:51, Daniel Wagner wrote:
> When the target executes a disconnect and the host triggers a reconnect
> immediately, the reconnect command still finds an existing association.
>
> The reconnect crashes later on because nvmet_fc_delete_target_assoc
> blindly removes resources while the reconnect code wants to use it.
>
> To address this, nvmet_fc_find_target_assoc should not be able to
> lookup an association which is being removed. The association list
> is already under RCU lifetime management, so let's properly use it
> and remove the association from the list and wait for a grace period
> before cleaning up all. This means we also can drop the RCU management
> on the queues, because this is now handled via the association itself.
>
> A second step split the execution context so that the initial disconnect
> command can complete without running the reconnect code in the same
> context. As usual, this is done by deferring the ->done to a workqueue.
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
> ---
>   drivers/nvme/target/fc.c | 83 ++++++++++++++++++----------------------
>   1 file changed, 37 insertions(+), 46 deletions(-)
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
hare@xxxxxxx                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Ivo Totev, Andrew McDonald,
Werner Knoblich