scsi: libfc: fix a deadlock in fc_rport_work

In places like fc_rport_recv_plogi_req and fcoe_ctlr_vn_add we always
take the lport disc_mutex lock before the rports mutex
(rp_mutex) lock. Gaurding list_del_rcu(&rdata->peers) with
disc.disc_mutex in fc_rport_work is correct but the rp_mutex lock
can and should to be dropped before taking that lock else results
in a deadlock.

Signed-off-by: Satish Kharat <satishkh@cisco.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index 5203258..31d31aa 100644 (file)
--- a/drivers/scsi/libfc/fc_rport.c
+++ b/drivers/scsi/libfc/fc_rport.c
@@ -383,11 +383,11 @@ static void fc_rport_work(struct work_struct *work)
                                fc_rport_enter_flogi(rdata);
                                mutex_unlock(&rdata->rp_mutex);
                        } else {
+                               mutex_unlock(&rdata->rp_mutex);
                                FC_RPORT_DBG(rdata, "work delete\n");
                                mutex_lock(&lport->disc.disc_mutex);
                                list_del_rcu(&rdata->peers);
                                mutex_unlock(&lport->disc.disc_mutex);
-                               mutex_unlock(&rdata->rp_mutex);
                                kref_put(&rdata->kref, fc_rport_destroy);
                        }
                } else {