[PATCH v1 2/2] nvme-fc: fix race with connectivity loss with nvme_fc_create_association

[Hannes Reinecke]

On 6/11/24 21:06, Daniel Wagner wrote:
> We are racing with nvme_fc_create_association here. We wouldn't have to
> do anything in nvme_fc_ctrl_connectivity_loss IF
> nvme_fc_create_association would reliable detect that the setup failed.
> In reality, nvme_fc_create_association is able to return success even
> though some of the operation fail during the setup (and this is even on
> purpose):
> 
>   nvme nvme10: NVME-FC{10}: create association : ...
>   nvme nvme10: NVME-FC{10}: controller connectivity lost. Awaiting Reconnect
>   nvme nvme10: queue_size 128 > ctrl maxcmd 32, reducing to maxcmd
>   nvme nvme10: Could not set queue count (880)
>   nvme nvme10: Failed to configure AEN (cfg 900)
>   nvme nvme10: NVME-FC{10}: controller connect complete
> 
> Thus we transition to the CONNECTED state and don't start the reconnect
> loop. Thus we should unconditionally schedule a reset.
> 
> If a reset has already been schedule it's either a no-op or we observe
> back to back reset. But we can't really distinguish between host side
> double scheduled reset work or a connectivity loss event right after a
> reset. Thus we have to live with this corner case. The system will enter
> the correct state eventually.
> 
> Signed-off-by: Daniel Wagner <dwagner at suse.de>
> ---
>   drivers/nvme/host/fc.c | 24 +++++++++++++++++++++---
>   1 file changed, 21 insertions(+), 3 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

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