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author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2017-03-04 17:57:35 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-03-07 23:09:59 +0100 |
commit | b21dd4506b71bdb9c5a20e759255cd2513ea7ebe (patch) | |
tree | 47be3cbc15140e37dfe4778a227a7a377390fe90 /net/rds/tcp.h | |
parent | rds: tcp: Reorder initialization sequence in rds_tcp_init to avoid races (diff) | |
download | linux-b21dd4506b71bdb9c5a20e759255cd2513ea7ebe.tar.xz linux-b21dd4506b71bdb9c5a20e759255cd2513ea7ebe.zip |
rds: tcp: Sequence teardown of listen and acceptor sockets to avoid races
Commit a93d01f5777e ("RDS: TCP: avoid bad page reference in
rds_tcp_listen_data_ready") added the function
rds_tcp_listen_sock_def_readable() to handle the case when a
partially set-up acceptor socket drops into rds_tcp_listen_data_ready().
However, if the listen socket (rtn->rds_tcp_listen_sock) is itself going
through a tear-down via rds_tcp_listen_stop(), the (*ready)() will be
null and we would hit a panic of the form
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: (null)
:
? rds_tcp_listen_data_ready+0x59/0xb0 [rds_tcp]
tcp_data_queue+0x39d/0x5b0
tcp_rcv_established+0x2e5/0x660
tcp_v4_do_rcv+0x122/0x220
tcp_v4_rcv+0x8b7/0x980
:
In the above case, it is not fatal to encounter a NULL value for
ready- we should just drop the packet and let the flush of the
acceptor thread finish gracefully.
In general, the tear-down sequence for listen() and accept() socket
that is ensured by this commit is:
rtn->rds_tcp_listen_sock = NULL; /* prevent any new accepts */
In rds_tcp_listen_stop():
serialize with, and prevent, further callbacks using lock_sock()
flush rds_wq
flush acceptor workq
sock_release(listen socket)
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/tcp.h')
-rw-r--r-- | net/rds/tcp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/rds/tcp.h b/net/rds/tcp.h index 9a1cc8906576..56ea6620fcf9 100644 --- a/net/rds/tcp.h +++ b/net/rds/tcp.h @@ -66,7 +66,7 @@ void rds_tcp_state_change(struct sock *sk); /* tcp_listen.c */ struct socket *rds_tcp_listen_init(struct net *); -void rds_tcp_listen_stop(struct socket *); +void rds_tcp_listen_stop(struct socket *sock, struct work_struct *acceptor); void rds_tcp_listen_data_ready(struct sock *sk); int rds_tcp_accept_one(struct socket *sock); int rds_tcp_keepalive(struct socket *sock); |