I can run some tests with this patch and report any results...
Regards,
Joy
On Sun, 2007-02-04 at 20:53 -0800, David Miller wrote:
> From: James Morris <[EMAIL PROTECTED]>
> Date: Thu, 1 Feb 2007 18:44:48 -0500 (EST)
>
> > A quick & dirty solution, which is what I think the BSD kernels do, is to
> > still drop the packet but just not return an error to the app. The app
> > then just sees a slight delay on the initial connection, as if a DNS
> > lookup took a bit longer than usual.
>
> I have another idea.
>
> Why don't we just flat-out ignore MSG_DONTWAIT for the socket
> visible cases, and handle connect() similarly?
>
> I think this is (just barely) legal, will be simple to implement, and
> will leave us with semantics that look like:
>
> 1) Sockets never see -EAGAIN due to SA resolution. They'll just
> pause until the route is resolved, even with O_NONBLOCK or
> MSG_DONTWAIT.
>
> 2) Asynchronous contexts such as ICMP replies and firewalling
> will still see the -EAGAIN and simply drop packets.
>
> These sleeps are legal because all of the socket paths involved
> have to be able to do lock_socket() (at a minimum) anyways.
>
> Something like this (untested) on the ipv4 side, for example:
>
> diff --git a/include/net/route.h b/include/net/route.h
> index 486e37a..a8af632 100644
> --- a/include/net/route.h
> +++ b/include/net/route.h
> @@ -146,7 +146,8 @@ static inline char rt_tos2priority(u8 tos)
>
> static inline int ip_route_connect(struct rtable **rp, __be32 dst,
> __be32 src, u32 tos, int oif, u8 protocol,
> - __be16 sport, __be16 dport, struct sock *sk)
> + __be16 sport, __be16 dport, struct sock *sk,
> + int flags)
> {
> struct flowi fl = { .oif = oif,
> .nl_u = { .ip4_u = { .daddr = dst,
> @@ -168,7 +169,7 @@ static inline int ip_route_connect(struct rtable **rp,
> __be32 dst,
> *rp = NULL;
> }
> security_sk_classify_flow(sk, &fl);
> - return ip_route_output_flow(rp, &fl, sk, 0);
> + return ip_route_output_flow(rp, &fl, sk, 1);
> }
>
> static inline int ip_route_newports(struct rtable **rp, u8 protocol,
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index 90c74b4..fa2c982 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -72,7 +72,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr
> *uaddr, int addr_len)
> tmp = ip_route_connect(&rt, nexthop, inet->saddr,
> RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
> IPPROTO_DCCP,
> - inet->sport, usin->sin_port, sk);
> + inet->sport, usin->sin_port, sk, 1);
> if (tmp < 0)
> return tmp;
>
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 8640096..5750a2b 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1007,7 +1007,7 @@ static int inet_sk_reselect_saddr(struct sock *sk)
> RT_CONN_FLAGS(sk),
> sk->sk_bound_dev_if,
> sk->sk_protocol,
> - inet->sport, inet->dport, sk);
> + inet->sport, inet->dport, sk, 0);
> if (err)
> return err;
>
> diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
> index 7b068a8..0072d79 100644
> --- a/net/ipv4/datagram.c
> +++ b/net/ipv4/datagram.c
> @@ -49,7 +49,7 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr
> *uaddr, int addr_len)
> err = ip_route_connect(&rt, usin->sin_addr.s_addr, saddr,
> RT_CONN_FLAGS(sk), oif,
> sk->sk_protocol,
> - inet->sport, usin->sin_port, sk);
> + inet->sport, usin->sin_port, sk, 1);
> if (err)
> return err;
> if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index a6c63bb..fed6a1e 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -489,7 +489,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock
> *sk, struct msghdr *msg,
> }
>
> security_sk_classify_flow(sk, &fl);
> - err = ip_route_output_flow(&rt, &fl, sk,
> !(msg->msg_flags&MSG_DONTWAIT));
> + err = ip_route_output_flow(&rt, &fl, sk, 1);
> }
> if (err)
> goto done;
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index f061ec5..383e4b5 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -191,7 +191,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr
> *uaddr, int addr_len)
> tmp = ip_route_connect(&rt, nexthop, inet->saddr,
> RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
> IPPROTO_TCP,
> - inet->sport, usin->sin_port, sk);
> + inet->sport, usin->sin_port, sk, 1);
> if (tmp < 0)
> return tmp;
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index cfff930..8b54c68 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -629,7 +629,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk,
> struct msghdr *msg,
> { .sport = inet->sport,
> .dport = dport } } };
> security_sk_classify_flow(sk, &fl);
> - err = ip_route_output_flow(&rt, &fl, sk,
> !(msg->msg_flags&MSG_DONTWAIT));
> + err = ip_route_output_flow(&rt, &fl, sk, 1);
> if (err)
> goto out;
>
> -
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