RDMA/cm: Allow ib_send_cm_drep() to be done under lock

The first thing ib_send_cm_drep() does is obtain the lock, so use the
usual unlocked wrapper, locked actor pattern here.

This avoids a sketchy lock/unlock sequence (which could allow state to
change) during cm_destroy_id().

Link: https://lore.kernel.org/r/20200310092545.251365-13-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 00bbfa2..8ed2534 100644 (file)
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -85,6 +85,8 @@ static void cm_add_one(struct ib_device *device);
 static void cm_remove_one(struct ib_device *device, void *client_data);
 static int cm_send_dreq_locked(struct cm_id_private *cm_id_priv,
                               const void *private_data, u8 private_data_len);
+static int cm_send_drep_locked(struct cm_id_private *cm_id_priv,
+                              void *private_data, u8 private_data_len);
 
 static struct ib_client cm_client = {
        .name   = "cm",
@@ -1100,8 +1102,8 @@ retest:
                spin_unlock_irq(&cm_id_priv->lock);
                break;
        case IB_CM_DREQ_RCVD:
+               cm_send_drep_locked(cm_id_priv, NULL, 0);
                spin_unlock_irq(&cm_id_priv->lock);
-               ib_send_cm_drep(cm_id, NULL, 0);
                break;
        default:
                spin_unlock_irq(&cm_id_priv->lock);
@@ -2685,51 +2687,60 @@ static void cm_format_drep(struct cm_drep_msg *drep_msg,
                            private_data_len);
 }
 
-int ib_send_cm_drep(struct ib_cm_id *cm_id,
-                   const void *private_data,
-                   u8 private_data_len)
+static int cm_send_drep_locked(struct cm_id_private *cm_id_priv,
+                              void *private_data, u8 private_data_len)
 {
-       struct cm_id_private *cm_id_priv;
        struct ib_mad_send_buf *msg;
-       unsigned long flags;
-       void *data;
        int ret;
 
+       lockdep_assert_held(&cm_id_priv->lock);
+
        if (private_data && private_data_len > IB_CM_DREP_PRIVATE_DATA_SIZE)
                return -EINVAL;
 
-       data = cm_copy_private_data(private_data, private_data_len);
-       if (IS_ERR(data))
-               return PTR_ERR(data);
-
-       cm_id_priv = container_of(cm_id, struct cm_id_private, id);
-       spin_lock_irqsave(&cm_id_priv->lock, flags);
-       if (cm_id->state != IB_CM_DREQ_RCVD) {
-               pr_debug("%s: local_id %d, cm_idcm_id->state(%d) != IB_CM_DREQ_RCVD\n",
-                        __func__, be32_to_cpu(cm_id->local_id), cm_id->state);
-               spin_unlock_irqrestore(&cm_id_priv->lock, flags);
-               kfree(data);
+       if (cm_id_priv->id.state != IB_CM_DREQ_RCVD) {
+               pr_debug(
+                       "%s: local_id %d, cm_idcm_id->state(%d) != IB_CM_DREQ_RCVD\n",
+                       __func__, be32_to_cpu(cm_id_priv->id.local_id),
+                       cm_id_priv->id.state);
+               kfree(private_data);
                return -EINVAL;
        }
 
-       cm_set_private_data(cm_id_priv, data, private_data_len);
+       cm_set_private_data(cm_id_priv, private_data, private_data_len);
        cm_enter_timewait(cm_id_priv);
 
        ret = cm_alloc_msg(cm_id_priv, &msg);
        if (ret)
-               goto out;
+               return ret;
 
        cm_format_drep((struct cm_drep_msg *) msg->mad, cm_id_priv,
                       private_data, private_data_len);
 
        ret = ib_post_send_mad(msg, NULL);
        if (ret) {
-               spin_unlock_irqrestore(&cm_id_priv->lock, flags);
                cm_free_msg(msg);
                return ret;
        }
+       return 0;
+}
 
-out:   spin_unlock_irqrestore(&cm_id_priv->lock, flags);
+int ib_send_cm_drep(struct ib_cm_id *cm_id, const void *private_data,
+                   u8 private_data_len)
+{
+       struct cm_id_private *cm_id_priv =
+               container_of(cm_id, struct cm_id_private, id);
+       unsigned long flags;
+       void *data;
+       int ret;
+
+       data = cm_copy_private_data(private_data, private_data_len);
+       if (IS_ERR(data))
+               return PTR_ERR(data);
+
+       spin_lock_irqsave(&cm_id_priv->lock, flags);
+       ret = cm_send_drep_locked(cm_id_priv, data, private_data_len);
+       spin_unlock_irqrestore(&cm_id_priv->lock, flags);
        return ret;
 }
 EXPORT_SYMBOL(ib_send_cm_drep);