diff options
author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2021-11-26 17:15:29 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2021-11-29 12:12:36 +0000 |
commit | fd888e85fe6b661e78044dddfec0be5271afa626 (patch) | |
tree | c1ef71d45fd053e110de5aeea2b0eb02b1e2c681 /net/core | |
parent | 07b8ca3792dec6bc3288b08ff85d80b5330de1d6 (diff) |
net: Write lock dev_base_lock without disabling bottom halves.
The writer acquires dev_base_lock with disabled bottom halves.
The reader can acquire dev_base_lock without disabling bottom halves
because there is no writer in softirq context.
On PREEMPT_RT the softirqs are preemptible and local_bh_disable() acts
as a lock to ensure that resources, that are protected by disabling
bottom halves, remain protected.
This leads to a circular locking dependency if the lock acquired with
disabled bottom halves (as in write_lock_bh()) and somewhere else with
enabled bottom halves (as by read_lock() in netstat_show()) followed by
disabling bottom halves (cxgb_get_stats() -> t4_wr_mbox_meat_timeout()
-> spin_lock_bh()). This is the reverse locking order.
All read_lock() invocation are from sysfs callback which are not invoked
from softirq context. Therefore there is no need to disable bottom
halves while acquiring a write lock.
Acquire the write lock of dev_base_lock without disabling bottom halves.
Reported-by: Pei Zhang <pezhang@redhat.com>
Reported-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r-- | net/core/dev.c | 16 | ||||
-rw-r--r-- | net/core/link_watch.c | 4 | ||||
-rw-r--r-- | net/core/rtnetlink.c | 8 |
3 files changed, 14 insertions, 14 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 823917de0d2b..d30adecc2bb2 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -365,12 +365,12 @@ static void list_netdevice(struct net_device *dev) ASSERT_RTNL(); - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); list_add_tail_rcu(&dev->dev_list, &net->dev_base_head); netdev_name_node_add(net, dev->name_node); hlist_add_head_rcu(&dev->index_hlist, dev_index_hash(net, dev->ifindex)); - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); dev_base_seq_inc(net); } @@ -383,11 +383,11 @@ static void unlist_netdevice(struct net_device *dev) ASSERT_RTNL(); /* Unlink dev from the device chain */ - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); list_del_rcu(&dev->dev_list); netdev_name_node_del(dev->name_node); hlist_del_rcu(&dev->index_hlist); - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); dev_base_seq_inc(dev_net(dev)); } @@ -1188,15 +1188,15 @@ rollback: netdev_adjacent_rename_links(dev, oldname); - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); netdev_name_node_del(dev->name_node); - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); synchronize_rcu(); - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); netdev_name_node_add(net, dev->name_node); - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev); ret = notifier_to_errno(ret); diff --git a/net/core/link_watch.c b/net/core/link_watch.c index 1a455847da54..9599afd0862d 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -55,7 +55,7 @@ static void rfc2863_policy(struct net_device *dev) if (operstate == dev->operstate) return; - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); switch(dev->link_mode) { case IF_LINK_MODE_TESTING: @@ -74,7 +74,7 @@ static void rfc2863_policy(struct net_device *dev) dev->operstate = operstate; - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); } diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 6f25c0a8aebe..d6eba554b137 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -842,9 +842,9 @@ static void set_operstate(struct net_device *dev, unsigned char transition) } if (dev->operstate != operstate) { - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); dev->operstate = operstate; - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); netdev_state_change(dev); } } @@ -2778,11 +2778,11 @@ static int do_setlink(const struct sk_buff *skb, if (tb[IFLA_LINKMODE]) { unsigned char value = nla_get_u8(tb[IFLA_LINKMODE]); - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); if (dev->link_mode ^ value) status |= DO_SETLINK_NOTIFY; dev->link_mode = value; - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); } if (tb[IFLA_VFINFO_LIST]) { |