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

Daniel Wagner
2023-12-18T16:07:29Z

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.

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) {
--
2.43.0