From 9cd3e072b0be17446e37d7414eac8a3499e0601e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 29 Nov 2015 20:03:10 -0800 Subject: net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA This patch is a cleanup to make following patch easier to review. Goal is to move SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA from (struct socket)->flags to a (struct socket_wq)->flags to benefit from RCU protection in sock_wake_async() To ease backports, we rename both constants. Two new helpers, sk_set_bit(int nr, struct sock *sk) and sk_clear_bit(int net, struct sock *sk) are added so that following patch can change their implementation. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/stream.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/core/stream.c') diff --git a/net/core/stream.c b/net/core/stream.c index d70f77a0c889..43309428644d 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -126,7 +126,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p) current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2; while (1) { - set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); @@ -139,7 +139,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p) } if (signal_pending(current)) goto do_interrupted; - clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); if (sk_stream_memory_free(sk) && !vm_wait) break; -- cgit v1.2.3 From ceb5d58b217098a657f3850b7a2640f995032e62 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 29 Nov 2015 20:03:11 -0800 Subject: net: fix sock_wake_async() rcu protection Dmitry provided a syzkaller (http://github.com/google/syzkaller) triggering a fault in sock_wake_async() when async IO is requested. Said program stressed af_unix sockets, but the issue is generic and should be addressed in core networking stack. The problem is that by the time sock_wake_async() is called, we should not access the @flags field of 'struct socket', as the inode containing this socket might be freed without further notice, and without RCU grace period. We already maintain an RCU protected structure, "struct socket_wq" so moving SOCKWQ_ASYNC_NOSPACE & SOCKWQ_ASYNC_WAITDATA into it is the safe route. It also reduces number of cache lines needing dirtying, so might provide a performance improvement anyway. In followup patches, we might move remaining flags (SOCK_NOSPACE, SOCK_PASSCRED, SOCK_PASSSEC) to save 8 bytes and let 'struct socket' being mostly read and let it being shared between cpus. Reported-by: Dmitry Vyukov Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/stream.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/core/stream.c') diff --git a/net/core/stream.c b/net/core/stream.c index 43309428644d..b96f7a79e544 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -39,7 +39,7 @@ void sk_stream_write_space(struct sock *sk) wake_up_interruptible_poll(&wq->wait, POLLOUT | POLLWRNORM | POLLWRBAND); if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN)) - sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT); + sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT); rcu_read_unlock(); } } -- cgit v1.2.3