From d8b5d43a04fba8ba09d5bb3c745808964f371d80 Mon Sep 17 00:00:00 2001 From: Jesse Gross Date: Mon, 26 Apr 2010 18:08:54 -0700 Subject: [PATCH] datapath: Don't hold dp_mutex when setting internal devs MTU. We currently acquire dp_mutex when we are notified that the MTU of a device attached to the datapath has changed so that we can set the internal devices to the minimum MTU. However, it is not required to hold dp_mutex because we already have RTNL lock and it causes a deadlock, so don't do it. Specifically, the issue is that DP mutex is acquired twice: once in dp_device_event() before calling set_internal_devs_mtu() and then again in internal_dev_change_mtu() when it is actually being changed (since the MTU can also be set directly). Since it's not a recursive mutex, deadlock. --- datapath/datapath.c | 5 ++--- datapath/dp_notify.c | 5 +---- datapath/vport-internal_dev.c | 8 +------- 3 files changed, 4 insertions(+), 14 deletions(-) diff --git a/datapath/datapath.c b/datapath/datapath.c index 83dd76fef..71a44e6fc 100644 --- a/datapath/datapath.c +++ b/datapath/datapath.c @@ -428,8 +428,7 @@ got_port_no: if (err) goto out_unlock_dp; - if (!(port.flags & ODP_PORT_INTERNAL)) - set_internal_devs_mtu(dp); + set_internal_devs_mtu(dp); dp_sysfs_add_if(dp->ports[port_no]); err = __put_user(port_no, &portp->port); @@ -1358,7 +1357,7 @@ int dp_min_mtu(const struct datapath *dp) } /* Sets the MTU of all datapath devices to the minimum of the ports. Must - * be called with RTNL lock and dp_mutex. */ + * be called with RTNL lock. */ void set_internal_devs_mtu(const struct datapath *dp) { struct dp_port *p; diff --git a/datapath/dp_notify.c b/datapath/dp_notify.c index 4a16a93fd..e73a731a3 100644 --- a/datapath/dp_notify.c +++ b/datapath/dp_notify.c @@ -54,11 +54,8 @@ static int dp_device_event(struct notifier_block *unused, unsigned long event, break; case NETDEV_CHANGEMTU: - if (!is_internal_dev(dev)) { - mutex_lock(&dp->mutex); + if (!is_internal_dev(dev)) set_internal_devs_mtu(dp); - mutex_unlock(&dp->mutex); - } break; } return NOTIFY_DONE; diff --git a/datapath/vport-internal_dev.c b/datapath/vport-internal_dev.c index 39283e052..88b6cc192 100644 --- a/datapath/vport-internal_dev.c +++ b/datapath/vport-internal_dev.c @@ -144,13 +144,7 @@ static int internal_dev_change_mtu(struct net_device *netdev, int new_mtu) return -EINVAL; if (dp_port) { - int min_mtu; - - mutex_lock(&dp_port->dp->mutex); - min_mtu = dp_min_mtu(dp_port->dp); - mutex_unlock(&dp_port->dp->mutex); - - if (new_mtu > min_mtu) + if (new_mtu > dp_min_mtu(dp_port->dp)) return -EINVAL; } -- 2.43.0