net: ibmveth: make veth_pool_store stop hanging

Use rtnl_mutex to synchronize veth_pool_store with itself,
ibmveth_close and ibmveth_open, preventing multiple calls in a row to
napi_disable.

Signed-off-by: Dave Marquardt <[email protected]>
Fixes: 860f242 ("[PATCH] ibmveth change buffer pools dynamically")
Reviewed-by: Nick Child <[email protected]>
Signed-off-by: NipaLocal <nipa@local>

Author: Dave Marquardt

drivers/net/ethernet/ibm/ibmveth.c

@@ -1802,18 +1802,24 @@ static ssize_t veth_pool_store(struct kobject *kobj, struct attribute *attr,
 	long value = simple_strtol(buf, NULL, 10);
 	long rc;
 
+	rtnl_lock();
+
 	if (attr == &veth_active_attr) {
 		if (value && !pool->active) {
 			if (netif_running(netdev)) {
 				if (ibmveth_alloc_buffer_pool(pool)) {
 					netdev_err(netdev,
 						   "unable to alloc pool\n");
+					rtnl_unlock();
 					return -ENOMEM;
 				}
 				pool->active = 1;
 				ibmveth_close(netdev);
-				if ((rc = ibmveth_open(netdev)))
+				rc = ibmveth_open(netdev);
+				if (rc) {
+					rtnl_unlock();
 					return rc;
+				}
 			} else {
 				pool->active = 1;
 			}
@@ -1833,44 +1839,57 @@ static ssize_t veth_pool_store(struct kobject *kobj, struct attribute *attr,
 
 			if (i == IBMVETH_NUM_BUFF_POOLS) {
 				netdev_err(netdev, "no active pool >= MTU\n");
+				rtnl_unlock();
 				return -EPERM;
 			}
 
 			if (netif_running(netdev)) {
 				ibmveth_close(netdev);
 				pool->active = 0;
-				if ((rc = ibmveth_open(netdev)))
+				rc = ibmveth_open(netdev);
+				if (rc) {
+					rtnl_unlock();
 					return rc;
+				}
 			}
 			pool->active = 0;
 		}
 	} else if (attr == &veth_num_attr) {
 		if (value <= 0 || value > IBMVETH_MAX_POOL_COUNT) {
+			rtnl_unlock();
 			return -EINVAL;
 		} else {
 			if (netif_running(netdev)) {
 				ibmveth_close(netdev);
 				pool->size = value;
-				if ((rc = ibmveth_open(netdev)))
+				rc = ibmveth_open(netdev);
+				if (rc) {
+					rtnl_unlock();
 					return rc;
+				}
 			} else {
 				pool->size = value;
 			}
 		}
 	} else if (attr == &veth_size_attr) {
 		if (value <= IBMVETH_BUFF_OH || value > IBMVETH_MAX_BUF_SIZE) {
+			rtnl_unlock();
 			return -EINVAL;
 		} else {
 			if (netif_running(netdev)) {
 				ibmveth_close(netdev);
 				pool->buff_size = value;
-				if ((rc = ibmveth_open(netdev)))
+				rc = ibmveth_open(netdev);
+				if (rc) {
+					rtnl_unlock();
 					return rc;
+				}
 			} else {
 				pool->buff_size = value;
 			}
 		}
 	}
+	rtnl_unlock();
 
 	/* kick the interrupt handler to allocate/deallocate pools */
 	ibmveth_interrupt(netdev->irq, netdev);