From: Vladimir Oltean vladimir.oltean@nxp.com
[ Upstream commit d06f925f13976ab82167c93467c70a337a0a3cda ]
When using the felix driver (the only one which supports UC filtering and MC filtering) as a DSA master for a random other DSA switch, one can see the following stack trace when the downstream switch ports join a VLAN-aware bridge:
============================= WARNING: suspicious RCU usage ----------------------------- net/8021q/vlan_core.c:238 suspicious rcu_dereference_protected() usage!
stack backtrace: Workqueue: dsa_ordered dsa_slave_switchdev_event_work Call trace: lockdep_rcu_suspicious+0x170/0x210 vlan_for_each+0x8c/0x188 dsa_slave_sync_uc+0x128/0x178 __hw_addr_sync_dev+0x138/0x158 dsa_slave_set_rx_mode+0x58/0x70 __dev_set_rx_mode+0x88/0xa8 dev_uc_add+0x74/0xa0 dsa_port_bridge_host_fdb_add+0xec/0x180 dsa_slave_switchdev_event_work+0x7c/0x1c8 process_one_work+0x290/0x568
What it's saying is that vlan_for_each() expects rtnl_lock() context and it's not getting it, when it's called from the DSA master's ndo_set_rx_mode().
The caller of that - dsa_slave_set_rx_mode() - is the slave DSA interface's dsa_port_bridge_host_fdb_add() which comes from the deferred dsa_slave_switchdev_event_work().
We went to great lengths to avoid the rtnl_lock() context in that call path in commit 0faf890fc519 ("net: dsa: drop rtnl_lock from dsa_slave_switchdev_event_work"), and calling rtnl_lock() is simply not an option due to the possibility of deadlocking when calling dsa_flush_workqueue() from the call paths that do hold rtnl_lock() - basically all of them.
So, when the DSA master calls vlan_for_each() from its ndo_set_rx_mode(), the state of the 8021q driver on this device is really not protected from concurrent access by anything.
Looking at net/8021q/, I don't think that vlan_info->vid_list was particularly designed with RCU traversal in mind, so introducing an RCU read-side form of vlan_for_each() - vlan_for_each_rcu() - won't be so easy, and it also wouldn't be exactly what we need anyway.
In general I believe that the solution isn't in net/8021q/ anyway; vlan_for_each() is not cut out for this task. DSA doesn't need rtnl_lock() to be held per se - since it's not a netdev state change that we're blocking, but rather, just concurrent additions/removals to a VLAN list. We don't even need sleepable context - the callback of vlan_for_each() just schedules deferred work.
The proposed escape is to remove the dependency on vlan_for_each() and to open-code a non-sleepable, rtnl-free alternative to that, based on copies of the VLAN list modified from .ndo_vlan_rx_add_vid() and .ndo_vlan_rx_kill_vid().
Fixes: 64fdc5f341db ("net: dsa: sync unicast and multicast addresses for VLAN filters too") Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://lore.kernel.org/r/20230626154402.3154454-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/dsa.h | 12 +++++-- net/dsa/dsa.c | 2 +- net/dsa/slave.c | 84 ++++++++++++++++++++++++++++++++--------------- net/dsa/switch.c | 4 +-- net/dsa/switch.h | 3 ++ 5 files changed, 74 insertions(+), 31 deletions(-)
diff --git a/include/net/dsa.h b/include/net/dsa.h index ab0f0a5b08602..197c5a6ca8f7f 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -314,9 +314,17 @@ struct dsa_port { struct list_head fdbs; struct list_head mdbs;
- /* List of VLANs that CPU and DSA ports are members of. */ struct mutex vlans_lock; - struct list_head vlans; + union { + /* List of VLANs that CPU and DSA ports are members of. + * Access to this is serialized by the sleepable @vlans_lock. + */ + struct list_head vlans; + /* List of VLANs that user ports are members of. + * Access to this is serialized by netif_addr_lock_bh(). + */ + struct list_head user_vlans; + }; };
/* TODO: ideally DSA ports would have a single dp->link_dp member, diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c index 1afed89e03c00..ccbdb98109f80 100644 --- a/net/dsa/dsa.c +++ b/net/dsa/dsa.c @@ -1106,7 +1106,7 @@ static struct dsa_port *dsa_port_touch(struct dsa_switch *ds, int index) mutex_init(&dp->vlans_lock); INIT_LIST_HEAD(&dp->fdbs); INIT_LIST_HEAD(&dp->mdbs); - INIT_LIST_HEAD(&dp->vlans); + INIT_LIST_HEAD(&dp->vlans); /* also initializes &dp->user_vlans */ INIT_LIST_HEAD(&dp->list); list_add_tail(&dp->list, &dst->ports);
diff --git a/net/dsa/slave.c b/net/dsa/slave.c index 165bb2cb84316..527b1d576460f 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -27,6 +27,7 @@ #include "master.h" #include "netlink.h" #include "slave.h" +#include "switch.h" #include "tag.h"
struct dsa_switchdev_event_work { @@ -161,8 +162,7 @@ static int dsa_slave_schedule_standalone_work(struct net_device *dev, return 0; }
-static int dsa_slave_host_vlan_rx_filtering(struct net_device *vdev, int vid, - void *arg) +static int dsa_slave_host_vlan_rx_filtering(void *arg, int vid) { struct dsa_host_vlan_rx_filtering_ctx *ctx = arg;
@@ -170,6 +170,28 @@ static int dsa_slave_host_vlan_rx_filtering(struct net_device *vdev, int vid, ctx->addr, vid); }
+static int dsa_slave_vlan_for_each(struct net_device *dev, + int (*cb)(void *arg, int vid), void *arg) +{ + struct dsa_port *dp = dsa_slave_to_port(dev); + struct dsa_vlan *v; + int err; + + lockdep_assert_held(&dev->addr_list_lock); + + err = cb(arg, 0); + if (err) + return err; + + list_for_each_entry(v, &dp->user_vlans, list) { + err = cb(arg, v->vid); + if (err) + return err; + } + + return 0; +} + static int dsa_slave_sync_uc(struct net_device *dev, const unsigned char *addr) { @@ -180,18 +202,14 @@ static int dsa_slave_sync_uc(struct net_device *dev, .addr = addr, .event = DSA_UC_ADD, }; - int err;
dev_uc_add(master, addr);
if (!dsa_switch_supports_uc_filtering(dp->ds)) return 0;
- err = dsa_slave_schedule_standalone_work(dev, DSA_UC_ADD, addr, 0); - if (err) - return err; - - return vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, &ctx); + return dsa_slave_vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, + &ctx); }
static int dsa_slave_unsync_uc(struct net_device *dev, @@ -204,18 +222,14 @@ static int dsa_slave_unsync_uc(struct net_device *dev, .addr = addr, .event = DSA_UC_DEL, }; - int err;
dev_uc_del(master, addr);
if (!dsa_switch_supports_uc_filtering(dp->ds)) return 0;
- err = dsa_slave_schedule_standalone_work(dev, DSA_UC_DEL, addr, 0); - if (err) - return err; - - return vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, &ctx); + return dsa_slave_vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, + &ctx); }
static int dsa_slave_sync_mc(struct net_device *dev, @@ -228,18 +242,14 @@ static int dsa_slave_sync_mc(struct net_device *dev, .addr = addr, .event = DSA_MC_ADD, }; - int err;
dev_mc_add(master, addr);
if (!dsa_switch_supports_mc_filtering(dp->ds)) return 0;
- err = dsa_slave_schedule_standalone_work(dev, DSA_MC_ADD, addr, 0); - if (err) - return err; - - return vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, &ctx); + return dsa_slave_vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, + &ctx); }
static int dsa_slave_unsync_mc(struct net_device *dev, @@ -252,18 +262,14 @@ static int dsa_slave_unsync_mc(struct net_device *dev, .addr = addr, .event = DSA_MC_DEL, }; - int err;
dev_mc_del(master, addr);
if (!dsa_switch_supports_mc_filtering(dp->ds)) return 0;
- err = dsa_slave_schedule_standalone_work(dev, DSA_MC_DEL, addr, 0); - if (err) - return err; - - return vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, &ctx); + return dsa_slave_vlan_for_each(dev, dsa_slave_host_vlan_rx_filtering, + &ctx); }
void dsa_slave_sync_ha(struct net_device *dev) @@ -1759,6 +1765,7 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto, struct netlink_ext_ack extack = {0}; struct dsa_switch *ds = dp->ds; struct netdev_hw_addr *ha; + struct dsa_vlan *v; int ret;
/* User port... */ @@ -1782,8 +1789,17 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto, !dsa_switch_supports_mc_filtering(ds)) return 0;
+ v = kzalloc(sizeof(*v), GFP_KERNEL); + if (!v) { + ret = -ENOMEM; + goto rollback; + } + netif_addr_lock_bh(dev);
+ v->vid = vid; + list_add_tail(&v->list, &dp->user_vlans); + if (dsa_switch_supports_mc_filtering(ds)) { netdev_for_each_synced_mc_addr(ha, dev) { dsa_slave_schedule_standalone_work(dev, DSA_MC_ADD, @@ -1803,6 +1819,12 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto, dsa_flush_workqueue();
return 0; + +rollback: + dsa_port_host_vlan_del(dp, &vlan); + dsa_port_vlan_del(dp, &vlan); + + return ret; }
static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, @@ -1816,6 +1838,7 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, }; struct dsa_switch *ds = dp->ds; struct netdev_hw_addr *ha; + struct dsa_vlan *v; int err;
err = dsa_port_vlan_del(dp, &vlan); @@ -1832,6 +1855,15 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
netif_addr_lock_bh(dev);
+ v = dsa_vlan_find(&dp->user_vlans, &vlan); + if (!v) { + netif_addr_unlock_bh(dev); + return -ENOENT; + } + + list_del(&v->list); + kfree(v); + if (dsa_switch_supports_mc_filtering(ds)) { netdev_for_each_synced_mc_addr(ha, dev) { dsa_slave_schedule_standalone_work(dev, DSA_MC_DEL, diff --git a/net/dsa/switch.c b/net/dsa/switch.c index 8c9a9f94b756a..1a42f93173345 100644 --- a/net/dsa/switch.c +++ b/net/dsa/switch.c @@ -673,8 +673,8 @@ static bool dsa_port_host_vlan_match(struct dsa_port *dp, return false; }
-static struct dsa_vlan *dsa_vlan_find(struct list_head *vlan_list, - const struct switchdev_obj_port_vlan *vlan) +struct dsa_vlan *dsa_vlan_find(struct list_head *vlan_list, + const struct switchdev_obj_port_vlan *vlan) { struct dsa_vlan *v;
diff --git a/net/dsa/switch.h b/net/dsa/switch.h index 15e67b95eb6e1..ea034677da153 100644 --- a/net/dsa/switch.h +++ b/net/dsa/switch.h @@ -111,6 +111,9 @@ struct dsa_notifier_master_state_info { bool operational; };
+struct dsa_vlan *dsa_vlan_find(struct list_head *vlan_list, + const struct switchdev_obj_port_vlan *vlan); + int dsa_tree_notify(struct dsa_switch_tree *dst, unsigned long e, void *v); int dsa_broadcast(unsigned long e, void *v);