[PATCH 27/33] scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock

The fcport->unsol_ctx_head list is modified from several contexts without
a common lock. Entries are added in qla2xxx_process_purls_iocb() from the
response queue ISR (under the qpair qp_lock), while they are removed from
qla2xxx_process_purls_pkt() (DPC/purex worker), qla_nvme_xmt_ls_rsp()
(NVMe-FC transport callback) and qla_nvme_release_lsrsp_cmd_kref() (SRB
completion). The qpair qp_lock cannot serialize this per-fcport list since
multiqueue adapters add entries through different qpairs, so a concurrent
add and delete (or two concurrent deletes) can corrupt the list pointers.

Introduce a dedicated per-fcport spinlock, unsol_ctx_lock, initialized in
qla2x00_alloc_fcport(), and take it around every list_add_tail()/list_del()
on unsol_ctx_head. The add nests under the existing qp_lock; no delete path
takes qp_lock, so the lock order is consistent and deadlock free.

Fixes: 875386b98857 ("scsi: qla2xxx: Add Unsolicited LS Request and Response Support for NVMe")
Cc: [email protected]
Reported-by: Sashiko <[email protected]>
Signed-off-by: Nilesh Javali <[email protected]>
---
 drivers/scsi/qla2xxx/qla_def.h  | 2 ++
 drivers/scsi/qla2xxx/qla_init.c | 1 +
 drivers/scsi/qla2xxx/qla_nvme.c | 9 +++++++++
 3 files changed, 12 insertions(+)

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index 2684d785ecbf..97e2a1a9ce3f 100644
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -2645,6 +2645,8 @@ typedef struct fc_port {
 	struct list_head list;
 	struct scsi_qla_host *vha;
 	struct list_head unsol_ctx_head;
+	/* Serializes unsol_ctx_head against ISR, DPC and NVMe transport. */
+	spinlock_t unsol_ctx_lock;
 
 	unsigned int conf_compl_supported:1;
 	unsigned int deleted:2;
diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 36de0a0bbcc1..2b9a9c672ec6 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -5710,6 +5710,7 @@ qla2x00_alloc_fcport(scsi_qla_host_t *vha, gfp_t flags)
 	INIT_LIST_HEAD(&fcport->gnl_entry);
 	INIT_LIST_HEAD(&fcport->list);
 	INIT_LIST_HEAD(&fcport->unsol_ctx_head);
+	spin_lock_init(&fcport->unsol_ctx_lock);
 
 	INIT_LIST_HEAD(&fcport->sess_cmd_list);
 	spin_lock_init(&fcport->sess_cmd_lock);
diff --git a/drivers/scsi/qla2xxx/qla_nvme.c b/drivers/scsi/qla2xxx/qla_nvme.c
index 36b742f73abf..beccece1e7d9 100644
--- a/drivers/scsi/qla2xxx/qla_nvme.c
+++ b/drivers/scsi/qla2xxx/qla_nvme.c
@@ -257,7 +257,9 @@ static void qla_nvme_release_lsrsp_cmd_kref(struct kref *kref)
 
 	fd_rsp = uctx->fd_rsp;
 
+	spin_lock_irqsave(&uctx->fcport->unsol_ctx_lock, flags);
 	list_del(&uctx->elem);
+	spin_unlock_irqrestore(&uctx->fcport->unsol_ctx_lock, flags);
 
 	fd_rsp->done(fd_rsp);
 	kfree(uctx);
@@ -446,7 +448,9 @@ static int qla_nvme_xmt_ls_rsp(struct nvme_fc_local_port *lport,
 		qla_nvme_ls_reject_iocb(vha, ha->base_qpair, &a, true);
 		spin_unlock_irqrestore(ha->base_qpair->qp_lock_ptr, flags);
 	}
+	spin_lock_irqsave(&uctx->fcport->unsol_ctx_lock, flags);
 	list_del(&uctx->elem);
+	spin_unlock_irqrestore(&uctx->fcport->unsol_ctx_lock, flags);
 	kfree(uctx);
 	return rval;
 }
@@ -1332,7 +1336,9 @@ qla2xxx_process_purls_pkt(struct scsi_qla_host *vha, struct purex_item *item)
 			spin_unlock_irqrestore(vha->hw->base_qpair->qp_lock_ptr,
 					       flags);
 		}
+		spin_lock_irqsave(&uctx->fcport->unsol_ctx_lock, flags);
 		list_del(&uctx->elem);
+		spin_unlock_irqrestore(&uctx->fcport->unsol_ctx_lock, flags);
 		kfree(uctx);
 	}
 }
@@ -1374,6 +1380,7 @@ void qla2xxx_process_purls_iocb(void **pkt, struct rsp_que **rsp)
 	struct purex_item *item;
 	port_id_t d_id = {0};
 	port_id_t id = {0};
+	unsigned long flags;
 	u8 *opcode;
 	bool xmt_reject = false;
 
@@ -1439,7 +1446,9 @@ void qla2xxx_process_purls_iocb(void **pkt, struct rsp_que **rsp)
 	uctx->ox_id = p->ox_id;
 	qla_rport->uctx = uctx;
 	INIT_LIST_HEAD(&uctx->elem);
+	spin_lock_irqsave(&fcport->unsol_ctx_lock, flags);
 	list_add_tail(&uctx->elem, &fcport->unsol_ctx_head);
+	spin_unlock_irqrestore(&fcport->unsol_ctx_lock, flags);
 	item->purls_context = (void *)uctx;
 
 	ql_dbg(ql_dbg_unsol, vha, 0x2121,
-- 
2.47.3