[SCSI] ibmvfc: Fix rport add/delete race resulting in oops

Commit 43c8da907ccc656935d1085701f4db83385d8a59 introduced a race
condition which can occur when adding/deleting rports. There are
two possible threads now that can be deleting rports in the ibmvfc
driver, which can result in list_del being called twice, resulting
in an oops. This patch adds a new state to the ibmvfc_target struct
to indicate the target has been removed from the list and is in
the process of being deleted.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

2 files changed, 9 insertions, 0 deletions

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index bd96cecaa619..a13db5908426 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -433,6 +433,9 @@ static void ibmvfc_set_tgt_action(struct ibmvfc_target *tgt,
 {
         switch (tgt->action) {
         case IBMVFC_TGT_ACTION_DEL_RPORT:
+                if (action == IBMVFC_TGT_ACTION_DELETED_RPORT)
+                        tgt->action = action;
+        case IBMVFC_TGT_ACTION_DELETED_RPORT:
                 break;
         default:
                 if (action == IBMVFC_TGT_ACTION_DEL_RPORT)
@@ -4193,11 +4196,15 @@ static void ibmvfc_tgt_add_rport(struct ibmvfc_target *tgt)
         if (rport && tgt->action == IBMVFC_TGT_ACTION_DEL_RPORT) {
                 tgt_dbg(tgt, "Deleting rport\n");
                 list_del(&tgt->queue);
+                ibmvfc_set_tgt_action(tgt, IBMVFC_TGT_ACTION_DELETED_RPORT);
                 spin_unlock_irqrestore(vhost->host->host_lock, flags);
                 fc_remote_port_delete(rport);
                 del_timer_sync(&tgt->timer);
                 kref_put(&tgt->kref, ibmvfc_release_tgt);
                 return;
+        } else if (rport && tgt->action == IBMVFC_TGT_ACTION_DELETED_RPORT) {
+                spin_unlock_irqrestore(vhost->host->host_lock, flags);
+                return;
         }
 
         if (rport) {
@@ -4297,6 +4304,7 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
                                 rport = tgt->rport;
                                 tgt->rport = NULL;
                                 list_del(&tgt->queue);
+                                ibmvfc_set_tgt_action(tgt, IBMVFC_TGT_ACTION_DELETED_RPORT);
                                 spin_unlock_irqrestore(vhost->host->host_lock, flags);
                                 if (rport)
                                         fc_remote_port_delete(rport);
diff --git a/drivers/scsi/ibmvscsi/ibmvfc.h b/drivers/scsi/ibmvscsi/ibmvfc.h
index d7e8dcd90650..af48172112fa 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.h
+++ b/drivers/scsi/ibmvscsi/ibmvfc.h
@@ -597,6 +597,7 @@ enum ibmvfc_target_action {
         IBMVFC_TGT_ACTION_INIT,
         IBMVFC_TGT_ACTION_INIT_WAIT,
         IBMVFC_TGT_ACTION_DEL_RPORT,
+        IBMVFC_TGT_ACTION_DELETED_RPORT,
 };
 
 struct ibmvfc_target {