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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2022-05-05 10:53:53 +0900 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-05-05 16:44:49 -0700 |
| commit | 6997fbd7a3dafa754f81d541498ace35b43246d8 (patch) | |
| tree | 9903b4be70449cb3b8759040ed1b57bdf4d89ed4 /net/rds/tcp.c | |
| parent | 68533eb1fb197a413fd8612ebb88e111ade3beac (diff) | |
| download | linux-6997fbd7a3dafa754f81d541498ace35b43246d8.tar.gz linux-6997fbd7a3dafa754f81d541498ace35b43246d8.tar.bz2 linux-6997fbd7a3dafa754f81d541498ace35b43246d8.zip | |
net: rds: use maybe_get_net() when acquiring refcount on TCP sockets
Eric Dumazet is reporting addition on 0 problem at rds_tcp_tune(), for
delayed works queued in rds_wq might be invoked after a net namespace's
refcount already reached 0.
Since rds_tcp_exit_net() from cleanup_net() calls flush_workqueue(rds_wq),
it is guaranteed that we can instead use maybe_get_net() from delayed work
functions until rds_tcp_exit_net() returns.
Note that I'm not convinced that all works which might access a net
namespace are already queued in rds_wq by the moment rds_tcp_exit_net()
calls flush_workqueue(rds_wq). If some race is there, rds_tcp_exit_net()
will fail to wait for work functions, and kmem_cache_free() could be
called from net_free() before maybe_get_net() is called from
rds_tcp_tune().
Reported-by: Eric Dumazet <edumazet@google.com>
Fixes: 3a58f13a881ed351 ("net: rds: acquire refcount on TCP sockets")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/41d09faf-bc78-1a87-dfd1-c6d1b5984b61@I-love.SAKURA.ne.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/rds/tcp.c')
| -rw-r--r-- | net/rds/tcp.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/net/rds/tcp.c b/net/rds/tcp.c index 2f638f8b7b1e..73ee2771093d 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -487,11 +487,11 @@ struct rds_tcp_net { /* All module specific customizations to the RDS-TCP socket should be done in * rds_tcp_tune() and applied after socket creation. */ -void rds_tcp_tune(struct socket *sock) +bool rds_tcp_tune(struct socket *sock) { struct sock *sk = sock->sk; struct net *net = sock_net(sk); - struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid); + struct rds_tcp_net *rtn; tcp_sock_set_nodelay(sock->sk); lock_sock(sk); @@ -499,10 +499,15 @@ void rds_tcp_tune(struct socket *sock) * a process which created this net namespace terminated. */ if (!sk->sk_net_refcnt) { + if (!maybe_get_net(net)) { + release_sock(sk); + return false; + } sk->sk_net_refcnt = 1; - get_net_track(net, &sk->ns_tracker, GFP_KERNEL); + netns_tracker_alloc(net, &sk->ns_tracker, GFP_KERNEL); sock_inuse_add(net, 1); } + rtn = net_generic(net, rds_tcp_netid); if (rtn->sndbuf_size > 0) { sk->sk_sndbuf = rtn->sndbuf_size; sk->sk_userlocks |= SOCK_SNDBUF_LOCK; @@ -512,6 +517,7 @@ void rds_tcp_tune(struct socket *sock) sk->sk_userlocks |= SOCK_RCVBUF_LOCK; } release_sock(sk); + return true; } static void rds_tcp_accept_worker(struct work_struct *work) |