nvmet-fc: avoid deadlock on delete association path

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.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index c80b8a066fd17904cf45b2582a8659c9536a6ef5..3e0d391e631b1030392df4eb150ec585c986450f 100644 (file)
--- 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 {
@@ -247,6 +249,13 @@ 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);
 static int nvmet_fc_tgt_q_get(struct nvmet_fc_tgt_queue *queue);
 static void nvmet_fc_tgtport_put(struct nvmet_fc_tgtport *tgtport);
+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 int nvmet_fc_tgtport_get(struct nvmet_fc_tgtport *tgtport);
 static void nvmet_fc_handle_fcp_rqst(struct nvmet_fc_tgtport *tgtport,
                                        struct nvmet_fc_fcp_iod *fod);
@@ -358,7 +367,7 @@ __nvmet_fc_finish_ls_req(struct nvmet_fc_ls_req_op *lsop)
 
        if (!lsop->req_queued) {
                spin_unlock_irqrestore(&tgtport->lock, flags);
-               goto out_puttgtport;
+               goto out_putwork;
        }
 
        list_del(&lsop->lsreq_list);
@@ -371,8 +380,8 @@ __nvmet_fc_finish_ls_req(struct nvmet_fc_ls_req_op *lsop)
                                  (lsreq->rqstlen + lsreq->rsplen),
                                  DMA_BIDIRECTIONAL);
 
-out_puttgtport:
-       nvmet_fc_tgtport_put(tgtport);
+out_putwork:
+       queue_work(nvmet_wq, &tgtport->put_work);
 }
 
 static int
@@ -1396,6 +1405,7 @@ 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) {