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author | David S. Miller <davem@davemloft.net> | 2018-02-20 13:23:57 -0500 |
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committer | David S. Miller <davem@davemloft.net> | 2018-02-20 13:23:57 -0500 |
commit | b99fe0e28fe0ba7d6e17e234e1150f1d9e197632 (patch) | |
tree | 0ebe27833d80a4162d34b6b46c8bc20db85b9dac /net/core | |
parent | ibmvnic: Keep track of supplementary TX descriptors (diff) | |
parent | net: Queue net_cleanup_work only if there is first net added (diff) | |
download | linux-dev-b99fe0e28fe0ba7d6e17e234e1150f1d9e197632.tar.xz linux-dev-b99fe0e28fe0ba7d6e17e234e1150f1d9e197632.zip |
Merge branch 'net-Get-rid-of-net_mutex-and-simplify-cleanup_list-queueing'
Kirill Tkhai says:
====================
net: Get rid of net_mutex and simplify cleanup_list queueing
[1/3] kills net_mutex and makes net_sem be taken for write instead.
This is made to take less locks (1 instead of 2) for the time
before all pernet_operations are converted.
[2-3/3] simplifies dead net cleanup queueing, and makes llist api
be used for that.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r-- | net/core/net_namespace.c | 75 |
1 files changed, 39 insertions, 36 deletions
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index bcab9a938d6f..27a55236ad64 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -29,8 +29,6 @@ static LIST_HEAD(pernet_list); static struct list_head *first_device = &pernet_list; -/* Used only if there are !async pernet_operations registered */ -DEFINE_MUTEX(net_mutex); LIST_HEAD(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list); @@ -407,6 +405,7 @@ struct net *copy_net_ns(unsigned long flags, { struct ucounts *ucounts; struct net *net; + unsigned write; int rv; if (!(flags & CLONE_NEWNET)) @@ -424,20 +423,26 @@ struct net *copy_net_ns(unsigned long flags, refcount_set(&net->passive, 1); net->ucounts = ucounts; get_user_ns(user_ns); - - rv = down_read_killable(&net_sem); +again: + write = READ_ONCE(nr_sync_pernet_ops); + if (write) + rv = down_write_killable(&net_sem); + else + rv = down_read_killable(&net_sem); if (rv < 0) goto put_userns; - if (nr_sync_pernet_ops) { - rv = mutex_lock_killable(&net_mutex); - if (rv < 0) - goto up_read; + + if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) { + up_read(&net_sem); + goto again; } rv = setup_net(net, user_ns); - if (nr_sync_pernet_ops) - mutex_unlock(&net_mutex); -up_read: - up_read(&net_sem); + + if (write) + up_write(&net_sem); + else + up_read(&net_sem); + if (rv < 0) { put_userns: put_user_ns(user_ns); @@ -476,28 +481,33 @@ static void unhash_nsid(struct net *net, struct net *last) spin_unlock_bh(&net->nsid_lock); } -static DEFINE_SPINLOCK(cleanup_list_lock); -static LIST_HEAD(cleanup_list); /* Must hold cleanup_list_lock to touch */ +static LLIST_HEAD(cleanup_list); static void cleanup_net(struct work_struct *work) { const struct pernet_operations *ops; struct net *net, *tmp, *last; - struct list_head net_kill_list; + struct llist_node *net_kill_list; LIST_HEAD(net_exit_list); + unsigned write; /* Atomically snapshot the list of namespaces to cleanup */ - spin_lock_irq(&cleanup_list_lock); - list_replace_init(&cleanup_list, &net_kill_list); - spin_unlock_irq(&cleanup_list_lock); + net_kill_list = llist_del_all(&cleanup_list); +again: + write = READ_ONCE(nr_sync_pernet_ops); + if (write) + down_write(&net_sem); + else + down_read(&net_sem); - down_read(&net_sem); - if (nr_sync_pernet_ops) - mutex_lock(&net_mutex); + if (!write && unlikely(READ_ONCE(nr_sync_pernet_ops))) { + up_read(&net_sem); + goto again; + } /* Don't let anyone else find us. */ rtnl_lock(); - list_for_each_entry(net, &net_kill_list, cleanup_list) + llist_for_each_entry(net, net_kill_list, cleanup_list) list_del_rcu(&net->list); /* Cache last net. After we unlock rtnl, no one new net * added to net_namespace_list can assign nsid pointer @@ -512,7 +522,7 @@ static void cleanup_net(struct work_struct *work) last = list_last_entry(&net_namespace_list, struct net, list); rtnl_unlock(); - list_for_each_entry(net, &net_kill_list, cleanup_list) { + llist_for_each_entry(net, net_kill_list, cleanup_list) { unhash_nsid(net, last); list_add_tail(&net->exit_list, &net_exit_list); } @@ -528,14 +538,14 @@ static void cleanup_net(struct work_struct *work) list_for_each_entry_reverse(ops, &pernet_list, list) ops_exit_list(ops, &net_exit_list); - if (nr_sync_pernet_ops) - mutex_unlock(&net_mutex); - /* Free the net generic variables */ list_for_each_entry_reverse(ops, &pernet_list, list) ops_free_list(ops, &net_exit_list); - up_read(&net_sem); + if (write) + up_write(&net_sem); + else + up_read(&net_sem); /* Ensure there are no outstanding rcu callbacks using this * network namespace. @@ -563,8 +573,6 @@ static void cleanup_net(struct work_struct *work) void net_ns_barrier(void) { down_write(&net_sem); - mutex_lock(&net_mutex); - mutex_unlock(&net_mutex); up_write(&net_sem); } EXPORT_SYMBOL(net_ns_barrier); @@ -574,13 +582,8 @@ static DECLARE_WORK(net_cleanup_work, cleanup_net); void __put_net(struct net *net) { /* Cleanup the network namespace in process context */ - unsigned long flags; - - spin_lock_irqsave(&cleanup_list_lock, flags); - list_add(&net->cleanup_list, &cleanup_list); - spin_unlock_irqrestore(&cleanup_list_lock, flags); - - queue_work(netns_wq, &net_cleanup_work); + if (llist_add(&net->cleanup_list, &cleanup_list)) + queue_work(netns_wq, &net_cleanup_work); } EXPORT_SYMBOL_GPL(__put_net); |