Re: [PATCH v3 15/16] nvmet-fc: avoid deadlock on delete association path

Hannes Reinecke
2023-12-19T11:43:56Z

On 12/18/23 16:31, Daniel Wagner wrote:
> When deleting an association the shutdown path is deadlocking because we
> try to flush the nvmet_wq nested. Avoid this by deadlock by deferring
> the put work into its own work item.
>
Maybe deleting the first 'by' ?

> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> drivers/nvme/target/fc.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
> index 23d8779dc221..30ba4ede333f 100644
> --- a/drivers/nvme/target/fc.c
> +++ b/drivers/nvme/target/fc.c
> @@ -111,6 +111,8 @@ struct nvmet_fc_tgtport {
> struct nvmet_fc_port_entry *pe;
> struct kref ref;
> u32 max_sg_cnt;
> +
> + struct work_struct put_work;
> };
>
> struct nvmet_fc_port_entry {
> @@ -243,6 +245,13 @@ static LIST_HEAD(nvmet_fc_portentry_list);
>
> static void nvmet_fc_handle_ls_rqst_work(struct work_struct *work);
> static void nvmet_fc_fcp_rqst_op_defer_work(struct work_struct *work);
> +static void nvmet_fc_put_tgtport_work(struct work_struct *work)
> +{
> + struct nvmet_fc_tgtport *tgtport =
> + container_of(work, struct nvmet_fc_tgtport, put_work);
> +
> + nvmet_fc_tgtport_put(tgtport);
> +}
> static void nvmet_fc_tgt_a_put(struct nvmet_fc_tgt_assoc *assoc);
> static int nvmet_fc_tgt_a_get(struct nvmet_fc_tgt_assoc *assoc);
> static void nvmet_fc_tgt_q_put(struct nvmet_fc_tgt_queue *queue);
> @@ -359,7 +368,7 @@ __nvmet_fc_finish_ls_req(struct nvmet_fc_ls_req_op *lsop)
>
> if (!lsop->req_queued) {
> spin_unlock_irqrestore(&tgtport->lock, flags);
> - nvmet_fc_tgtport_put(tgtport);
> + queue_work(nvmet_wq, &tgtport->put_work);
> return;
> }
>
> @@ -373,7 +382,7 @@ __nvmet_fc_finish_ls_req(struct nvmet_fc_ls_req_op *lsop)
> (lsreq->rqstlen + lsreq->rsplen),
> DMA_BIDIRECTIONAL);
>
> - nvmet_fc_tgtport_put(tgtport);
> + queue_work(nvmet_wq, &tgtport->put_work);
> }
>
> static int
> @@ -1402,6 +1411,7 @@ nvmet_fc_register_targetport(struct nvmet_fc_port_info *pinfo,
> kref_init(&newrec->ref);
> ida_init(&newrec->assoc_cnt);
> newrec->max_sg_cnt = template->max_sgl_segments;
> + INIT_WORK(&newrec->put_work, nvmet_fc_put_tgtport_work);
>
> ret = nvmet_fc_alloc_ls_iodlist(newrec);
> if (ret) {
Otherwise:

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
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