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author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2017-03-04 08:57:34 -0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-03-07 14:09:59 -0800 |
commit | 16c09b1c7657522a321b04aa7f4300865b7cb292 (patch) | |
tree | f3376aef6bfad4e5efa89945dc0882a6d1d1bcae /net | |
parent | 8edc3affc0770886c7bfb3436b0fdd09bce13167 (diff) | |
download | blackbird-op-linux-16c09b1c7657522a321b04aa7f4300865b7cb292.tar.gz blackbird-op-linux-16c09b1c7657522a321b04aa7f4300865b7cb292.zip |
rds: tcp: Reorder initialization sequence in rds_tcp_init to avoid races
Order of initialization in rds_tcp_init needs to be done so
that resources are set up and destroyed in the correct synchronization
sequence with both the data path, as well as netns create/destroy
path. Specifically,
- we must call register_pernet_subsys and get the rds_tcp_netid
before calling register_netdevice_notifier, otherwise we risk
the sequence
1. register_netdevice_notifier sets up netdev notifier callback
2. rds_tcp_dev_event -> rds_tcp_kill_sock uses netid 0, and finds
the wrong rtn, resulting in a panic with string that is of the form:
BUG: unable to handle kernel NULL pointer dereference at 000000000000000d
IP: rds_tcp_kill_sock+0x3a/0x1d0 [rds_tcp]
:
- the rds_tcp_incoming_slab kmem_cache must be initialized before the
datapath starts up. The latter can happen any time after the
pernet_subsys registration of rds_tcp_net_ops, whose -> init
function sets up the listen socket. If the rds_tcp_incoming_slab has
not been set up at that time, a panic of the form below may be
encountered
BUG: unable to handle kernel NULL pointer dereference at 0000000000000014
IP: kmem_cache_alloc+0x90/0x1c0
:
rds_tcp_data_recv+0x1e7/0x370 [rds_tcp]
tcp_read_sock+0x96/0x1c0
rds_tcp_recv_path+0x65/0x80 [rds_tcp]
:
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/rds/tcp.c | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/net/rds/tcp.c b/net/rds/tcp.c index 65c8e3b3b710..fbf807a0cc4a 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -638,19 +638,19 @@ static int rds_tcp_init(void) goto out; } - ret = register_netdevice_notifier(&rds_tcp_dev_notifier); - if (ret) { - pr_warn("could not register rds_tcp_dev_notifier\n"); + ret = rds_tcp_recv_init(); + if (ret) goto out_slab; - } ret = register_pernet_subsys(&rds_tcp_net_ops); if (ret) - goto out_notifier; + goto out_recv; - ret = rds_tcp_recv_init(); - if (ret) + ret = register_netdevice_notifier(&rds_tcp_dev_notifier); + if (ret) { + pr_warn("could not register rds_tcp_dev_notifier\n"); goto out_pernet; + } rds_trans_register(&rds_tcp_transport); @@ -660,9 +660,8 @@ static int rds_tcp_init(void) out_pernet: unregister_pernet_subsys(&rds_tcp_net_ops); -out_notifier: - if (unregister_netdevice_notifier(&rds_tcp_dev_notifier)) - pr_warn("could not unregister rds_tcp_dev_notifier\n"); +out_recv: + rds_tcp_recv_exit(); out_slab: kmem_cache_destroy(rds_tcp_conn_slab); out: |